Chemistry Exam Review PDF

Science Exam Review Chemistry: Exploring the Fundamentals Chemistry Labeling Parts of an Atom An atom is the basic unit of matter, consisting of a nucleus surrounded by a cloud of electrons. The parts of an atom include: ​ Nucleus: The central core of an atom, containing protons and neutrons....

Science Exam Review Chemistry: Exploring the Fundamentals Chemistry Labeling Parts of an Atom An atom is the basic unit of matter, consisting of a nucleus surrounded by a cloud of electrons. The parts of an atom include: ​ Nucleus: The central core of an atom, containing protons and neutrons. ​ Protons: Positively charged particles found in the nucleus. ​ Neutrons: Neutral particles found in the nucleus, along with protons. ​ Electrons: Negatively charged particles that orbit the nucleus. Calculating Protons, Neutrons, and Electrons ​ The number of protons in an atom's nucleus determines the element's identity. ​ The number of neutrons in the nucleus can vary, creating different isotopes of the same element. ​ The number of electrons orbiting the nucleus is typically equal to the number of protons, giving the atom a neutral charge. To calculate the number of protons, neutrons, and electrons: ​ Protons = Atomic Number ​ Neutrons = Mass Number - Atomic Number ​ Electrons = Atomic Number (for a neutral atom) Identifying Chemical Properties vs. Physical Properties Chemical properties describe how a substance interacts with other substances and changes its composition, such as: ​ Reactivity ​ Flammability ​ pH ​ Solubility Physical properties describe the observable characteristics of a substance, such as:  ​ State (solid, liquid, gas) ​ Color ​ Density ​ Melting/Boiling Point Differentiating Between Pure Substances and Mixtures Pure Substances: ​ Consist of a single type of atom or molecule ​ Have a fixed composition ​ Examples: Oxygen (O₂), Sodium Chloride (NaCl) Mixtures: ​ Consist of two or more pure substances ​ Have a variable composition ​ Examples: Air, Seawater, Alloys Characteristics of Elements in the Same Group of the Periodic Table Elements in the same group (vertical column) of the periodic table share similar: ​ Electron configuration ​ Chemical properties ​ Reactivity This is because they have the same number of valence electrons, which are the electrons involved in chemical bonding. Classification of a Newly Discovered Element When a new element is discovered, it can be classified based on its properties and placement in the periodic table: ​ Determine the element's atomic number and mass number ​ Identify the element's electron configuration and valence electrons ​ Compare the element's properties to those of other elements in the same group and period ​ Assign the element to the appropriate group and period of the periodic table Understanding Metalloids Metalloids are elements that exhibit properties of both metals and nonmetals. They are located along the "staircase" on the periodic table, between the metals and nonmetals. Examples of metalloids include: ​ Silicon (Si) ​ Germanium (Ge) ​ Arsenic (As) ​ Antimony (Sb) ​ Tellurium (Te) Metalloids have a mix of metallic and nonmetallic characteristics, making them useful in various technological applications. Counting Atoms in Chemical Compounds To determine the number of atoms of each element in a chemical compound, look at the subscripts after the element symbols: ​ H2O - 2 hydrogen atoms, 1 oxygen atom ​ CO2 - 1 carbon atom, 2 oxygen atoms ​ C6H12O6 - 6 carbon atoms, 12 hydrogen atoms, 6 oxygen atoms Identifying Elements in Chemical Compounds The elements present in a chemical compound can be identified by the symbols in the compound's formula. For example: ​ NaCl - Sodium (Na) and Chlorine (Cl) ​ H2SO4 - Hydrogen (H), Sulfur (S), and Oxygen (O) ​ C3H8 - Carbon (C) and Hydrogen (H) Calculating Density Using GRASS Density is a physical property that describes the mass of a substance per unit volume. The formula for density is: D= M/V M= (D)(V) V= M/D To calculate density using the GRASS method: 1.​ Gather the mass and volume data 2.​ Record the units for mass and volume  3.​ Apply the density formula 4.​ Simplify the units to get the final density value 5.​ State the final density value with the correct units Drawing Bohr-Rutherford Diagrams Bohr-Rutherford diagrams are visual representations of an atom's structure, showing the arrangement of electrons around the nucleus. To draw a Bohr-Rutherford diagram: 1.​ Determine the element and its atomic number 2.​ Draw the nucleus with the appropriate number of protons 3.​ Arrange the electrons in circular shells around the nucleus, with the innermost shell filled first 4.​ Label the shells and indicate the number of electrons in each shell Determining Charges After Rubbing Materials Together Using Electrostatic Series When two materials are rubbed together, they can develop opposite electrical charges due to the transfer of electrons. The electrostatic series, also known as the triboelectric series, ranks materials based on their tendency to gain or lose electrons. ​ Materials higher in the series tend to lose electrons and become positively charged. ​ Materials lower in the series tend to gain electrons and become negatively charged. The strength of the charge developed depends on the position of the materials in the electrostatic series. Identifying Elements Based on Given Properties To identify an element based on its properties, you can use the periodic table and the following information: ​ Atomic number ​ Mass number ​ Electron configuration ​ Chemical properties (reactivity, melting/boiling point, etc.) ​ Physical properties (state, color, density, etc.) By comparing the given properties to the characteristics of elements in the periodic table, you can determine the identity of the unknown element. Properties of a Noble Gas Noble gases are a group of six elements on the periodic table: helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and radon (Rn). They share the following properties: ​ Extremely stable and unreactive ​ Colorless, odorless, and tasteless ​ Have full valence electron shells, making them very stable ​ Have high ionization energies, making them resistant to forming ions ​ Have low boiling and melting points due to weak intermolecular forces Properties of a Halogen Halogens are a group of five elements on the periodic table: fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At). They share the following properties: ​ Highly reactive nonmetals ​ Exist as diatomic molecules (e.g., $\ce{F2}$, $\ce{Cl2}$) ​ Have high electronegativity, meaning they strongly attract electrons ​ Form ionic bonds with metals to create salts (e.g., $\ce{NaCl}$) ​ Have a wide range of oxidation states, from -1 to +7 ​ Have low melting and boiling points compared to other nonmetals Physics: Circuits, Electricity, and Energy Parallel vs. Simple Circuits Parallel Circuits ​ In a parallel circuit, components are connected to the same voltage source in multiple paths. ​ The current in each branch is independent of the current in other branches. ​ The total current in a parallel circuit is the sum of the currents in each branch. ​ The voltage across each component in a parallel circuit is the same. ​ Advantages of parallel circuits: ○​ Components can be added or removed without affecting the rest of the circuit. ○​ Components can operate independently. ○​ If one component fails, the others will still function. ​ Disadvantages of parallel circuits: ○​ More complex to design and build.  ○​ Requires more wiring and components. ○​ Total current in the circuit can be high. Simple (Series) Circuits ​ In a simple (series) circuit, components are connected end-to-end in a single path. ​ The current is the same through each component in the circuit. ​ The total voltage in a series circuit is the sum of the voltages across each component. ​ Advantages of series circuits: ○​ Simpler to design and build. ○​ Requires less wiring and components. ○​ Total current in the circuit is lower. ​ Disadvantages of series circuits: ○​ If one component fails, the entire circuit stops working. ○​ Components must be added or removed carefully. ○​ Voltage across each component can vary. Calculating Current and Voltage Calculating Current in Parallel vs. Simple Circuits ​ In a parallel circuit, the total current is the sum of the currents in each branch:$I_{total} = I_1 + I_2 + I_3 +... + I_n$ ​ In a simple (series) circuit, the current is the same through each component:$I_{total} = I_1 = I_2 = I_3 =... = I_n$ Calculating Voltage in Parallel vs. Simple Circuits ​ In a parallel circuit, the voltage across each component is the same:$V_1 = V_2 = V_3 =... = V_n = V_{total}$ ​ In a simple (series) circuit, the total voltage is the sum of the voltages across each component:$V_{total} = V_1 + V_2 + V_3 +... + V_n$ Drawing Circuits ​ Parallel circuits are drawn with components connected to the same voltage source in multiple paths. ​ Series circuits are drawn with components connected end-to-end in a single path. Law of Electric Charges ​ Like charges repel, and opposite charges attract.  ​ The force between two charges is proportional to the product of the charges and inversely proportional to the square of the distance between them. ​ This is described by Coulomb's law: $F = k \frac{q_1 q_2}{r^2}$, where $k$ is the Coulomb constant. Hydroelectricity ​ Hydroelectricity is a renewable energy source that uses the power of flowing water to generate electricity. ​ Advantages of hydroelectricity: ○​ Renewable and sustainable ○​ Reliable and consistent power generation ○​ Low operating costs ○​ No greenhouse gas emissions ​ Disadvantages of hydroelectricity: ○​ Requires specific geographic locations with suitable water resources ○​ Can have environmental impacts on local ecosystems ○​ High initial construction costs Resistance and Non-Renewable Resources Factors Affecting Resistance of a Wire ​ The resistance of a wire is affected by: ○​ Length of the wire: Longer wires have higher resistance ○​ Cross-sectional area of the wire: Thicker wires have lower resistance ○​ Material of the wire: Different materials have different resistivities Non-Renewable Resources ​ Non-renewable resources are natural resources that cannot be replenished at the same rate they are consumed. ​ Examples of non-renewable resources: ○​ Fossil fuels (oil, natural gas, coal) ○​ Minerals and metals (iron, copper, gold) ○​ Nuclear fuels (uranium) ​ The use of non-renewable resources can have significant environmental impacts, such as greenhouse gas emissions and resource depletion. Ecology: Understanding the Process of Photosynthesis, Characteristics of Earth's Spheres, and Sustainable Practices Photosynthesis Photosynthesis is the process by which plants and other organisms convert light energy from the sun into chemical energy in the form of glucose. This process is essential for the survival of most life on Earth, as it provides the primary source of energy and food for many organisms. Key Points: ​ Photosynthesis occurs in the chloroplasts of plant cells, specifically in the chlorophyll-containing structures called thylakoids. ​ The overall equation for photosynthesis is:$6CO_2 + 6H_2O \rightarrow C_6H_{12}O_6 + 6O_2$ ​ The process involves two main stages: the light-dependent reactions and the light-independent reactions (also known as the Calvin cycle). ​ During the light-dependent reactions, chlorophyll absorbs light energy, which is used to split water molecules and produce ATP and NADPH. ​ In the light-independent reactions, the energy from ATP and NADPH is used to convert carbon dioxide into glucose. ​ Photosynthesis is the primary source of oxygen in the atmosphere, and it also helps to regulate the Earth's temperature and climate. Characteristics of Earth's Spheres The Earth is composed of four main spheres: the biosphere, atmosphere, hydrosphere, and lithosphere. Each of these spheres has unique characteristics and plays a crucial role in the overall functioning of the planet. Biosphere ​ The biosphere is the part of the Earth's environment that is inhabited by living organisms. ​ It includes all the ecosystems on the planet, from the deepest oceans to the highest mountains. ​ The biosphere is made up of both biotic (living) and abiotic (non-living) components.  ​ The atmosphere is the layer of gases surrounding the Earth that is retained by the planet's gravity. ​ It is composed primarily of nitrogen (78%), oxygen (21%), and other trace gases. ​ The atmosphere protects life on Earth by absorbing ultraviolet solar radiation, warming the surface through heat retention (greenhouse effect), and reducing temperature extremes between day and night. Hydrosphere ​ The hydrosphere is the combined mass of water found on, under, and above the surface of the Earth. ​ It includes all the water in the oceans, lakes, rivers, groundwater, glaciers, and atmospheric water vapor. ​ The hydrosphere is essential for the survival of all living organisms and plays a crucial role in the water cycle and climate regulation. Lithosphere ​ The lithosphere is the solid, outermost shell of the Earth, consisting of the crust and the uppermost portion of the mantle. ​ It is composed of various types of rock, including igneous, sedimentary, and metamorphic. ​ The lithosphere is divided into tectonic plates, which are constantly moving and interacting, causing geological processes such as earthquakes, volcanoes, and mountain formation. Biotic and Abiotic Factors in Ecosystems Ecosystems are made up of both biotic (living) and abiotic (non-living) factors. Understanding the interactions between these factors is crucial for understanding the overall functioning of an ecosystem. Biotic Factors: ​ Autotrophs: Organisms that can produce their own food through photosynthesis or chemosynthesis, such as plants, algae, and some bacteria. ​ Heterotrophs: Organisms that cannot produce their own food and must consume other organisms, such as animals, fungi, and some bacteria. Abiotic Factors: ​ Sunlight  ​ Water ​ Temperature ​ Soil composition ​ Atmospheric gases ​ Nutrients Threats to Ecosystem Sustainability Human activities can have significant negative impacts on the sustainability of Earth's ecosystems. Some of the main threats include: ​ Habitat destruction and fragmentation ​ Pollution (air, water, and soil) ​ Climate change ​ Overexploitation of natural resources ​ Invasive species introduction Sustainable Practices To promote the sustainability of Earth's ecosystems, various sustainable practices can be implemented, such as: ​ Renewable energy sources (solar, wind, hydroelectric) ​ Sustainable agriculture and forestry practices ​ Waste reduction, reuse, and recycling ​ Habitat restoration and conservation ​ Responsible resource management Energy Flow and Trophic Levels Energy flow in an ecosystem is typically represented by a food chain or food web, which shows the transfer of energy from one trophic level to the next. Trophic Levels: 1.​ Producers (autotrophs) 2.​ Primary consumers (herbivores) 3.​ Secondary consumers (carnivores that eat herbivores) 4.​ Tertiary consumers (carnivores that eat other carnivores) 5.​ Decomposers The energy available at each trophic level decreases due to the inefficiency of energy transfer and the loss of energy through heat and waste. Cellular Respiration Cellular respiration is the process by which organisms convert the chemical energy stored in glucose into a form that can be used by the cell, ATP. This process is the reverse of photosynthesis and occurs in the mitochondria of cells. The overall equation for cellular respiration is:$C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + ATP$ Water Cycle and the Hydrosphere The hydrosphere is the combined mass of water found on, under, and above the surface of the Earth. The water cycle, also known as the hydrologic cycle, is the continuous movement of water on, above, and below the Earth's surface. The main processes involved in the water cycle are: ​ Evaporation ​ Transpiration ​ Condensation ​ Precipitation ​ Surface runoff ​ Groundwater flow The water cycle is essential for the replenishment of freshwater resources and the regulation of the Earth's climate. Atmosphere and Climate The Earth's atmosphere plays a crucial role in regulating the planet's climate and temperature. The main characteristics of the atmosphere include: ​ Composition: Primarily nitrogen (78%), oxygen (21%), and other trace gases ​ Layers: Troposphere, stratosphere, mesosphere, thermosphere, and exosphere ​ Greenhouse effect: The trapping of heat by atmospheric gases, which helps maintain the Earth's temperature Human activities, such as the burning of fossil fuels and deforestation, can disrupt the balance of the atmosphere and contribute to climate change, which can have severe consequences for the sustainability of Earth's ecosystems. Analyzing Food Chains and Webs Food chains and food webs are visual representations of the flow of energy and the relationships between different organisms in an ecosystem. By analyzing these diagrams, you can: ​ Identify the producers, consumers, and decomposers ​ Determine the trophic levels of the organisms ​ Understand the energy flow and transfer between trophic levels ​ Recognize the interconnectedness of the ecosystem Analyzing food chains and webs can provide valuable insights into the dynamics and sustainability of an ecosystem. Earth and Space: Hertzsprung-Russell Diagram, Galaxies, Comets, and More Hertzsprung-Russell Diagram The Hertzsprung-Russell (H-R) diagram is a scatter plot that shows the relationship between the absolute magnitude (brightness) and the spectral classification (color) of stars. It is a fundamental tool in stellar astronomy and provides insights into the properties and evolution of stars. ​ Absolute Magnitude: The intrinsic brightness of a star, or the brightness it would have if it were located 10 parsecs (32.6 light-years) from Earth. ​ Spectral Classification: A scheme that categorizes stars based on their surface temperature, with the hottest stars classified as O-type and the coolest as M-type. ​ Main Sequence: The diagonal band where most stars, including our Sun, are located on the H-R diagram. Stars on the main sequence are fusing hydrogen into helium in their cores. ​ Giant Stars: Stars that have expanded and cooled, moving off the main sequence and into the upper-right portion of the H-R diagram. ​ Dwarf Stars: Stars that are smaller and denser than the Sun, occupying the lower-left portion of the H-R diagram. Types of Galaxies Galaxies are vast collections of stars, gas, and dust held together by gravity. There are several different types of galaxies, each with its own distinctive characteristics: Galaxy Type Description Spiral Characterized by a central bulge and spiral arms winding outward from the Galaxies center. Our Milky Way galaxy is a spiral galaxy. Elliptical Elliptical in shape, with no distinct spiral arms or central bulge. They are Galaxies generally older and more uniform in appearance. Irregular Galaxies that do not fit into the spiral or elliptical categories, often with an Galaxies asymmetric or chaotic appearance. Defining a Galaxy A galaxy is a gravitationally bound system of stars, stellar remnants, interstellar gas, dust, and dark matter. Galaxies range in size from dwarfs with just a few hundred million stars to giants with one trillion stars, each orbiting its galaxy's center of mass. Characteristics of Comets Comets are small, icy objects in the solar system that orbit the Sun. When a comet's orbit brings it close to the Sun, it heats up and releases gases and dust, forming a visible atmosphere or "coma" and sometimes a tail. ​ Nucleus: The solid, central part of a comet, typically a few kilometers in diameter, composed of ice, dust, and small rocky particles. ​ Coma: The atmosphere surrounding the nucleus, created by the sublimation of ice in the comet's nucleus as it approaches the Sun. ​ Tail: The stream of dust and ionized gases that extends millions of kilometers from the nucleus, always pointing away from the Sun due to the effects of solar radiation and solar wind. ​ Perihelion: The point in a comet's orbit when it is closest to the Sun.  ​ Aphelion: The point in a comet's orbit when it is farthest from the Sun. Star Temperatures and Colors The color of a star is directly related to its surface temperature: ​ Blue Stars: Extremely hot, with surface temperatures above 10,000 K (Kelvin). ​ White Stars: Moderately hot, with surface temperatures between 7,500 K and 10,000 K. ​ Yellow Stars: Intermediate temperature, with surface temperatures between 5,000 K and 7,500 K (our Sun is a yellow star). ​ Orange Stars: Relatively cool, with surface temperatures between 3,500 K and 5,000 K. ​ Red Stars: The coolest stars, with surface temperatures below 3,500 K. Facts about Earth ​ Diameter: Approximately 12,742 km (7,917 miles) ​ Surface Area: Approximately 510 million square km (197 million square miles) ​ Composition: Primarily iron and silicate rocks ​ Atmosphere: Nitrogen (78%), oxygen (21%), argon (0.9%), and other trace gases ​ Rotation Period: 23 hours, 56 minutes, 4 seconds (1 sidereal day) ​ Revolution Period: 365.25 days (1 year) Identifying Terrestrial Planets The four innermost planets in our solar system are known as the terrestrial planets: ​ Mercury: The smallest and closest planet to the Sun, with a rocky, cratered surface. ​ Venus: The second planet from the Sun, with a thick, toxic atmosphere and a surface temperature hot enough to melt lead. ​ Earth: The third planet from the Sun, the only known planet to harbor life, with a diverse range of ecosystems. ​ Mars: The fourth planet from the Sun, often called the "Red Planet" due to its reddish appearance, with a thin atmosphere and a surface covered in craters, volcanoes, and canyons. Conditions for a Lunar Eclipse A lunar eclipse occurs when the Moon passes through the Earth's shadow. This can only happen during a full moon, when the Moon is on the opposite side of the Earth from the Sun. The conditions for a lunar eclipse are:  1.​ The Moon must be in the full moon phase. 2.​ The Moon must pass through the Earth's umbra (the full shadow cast by the Earth). 3.​ The Moon, Earth, and Sun must be aligned in a straight line, with the Earth in the middle. Understanding Galaxies Galaxies are the building blocks of the universe, containing billions of stars, as well as gas, dust, and dark matter. They come in a variety of shapes and sizes, and their study provides insights into the evolution and structure of the cosmos. Key points about galaxies: ​ Galaxies are held together by the force of gravity, with the stars, gas, and dust orbiting the galaxy's center of mass. ​ The Milky Way galaxy, which contains our solar system, is a spiral galaxy with a central bulge and spiral arms. ​ Galaxies can be classified into three main types: spiral, elliptical, and irregular. ​ Galaxies interact and merge with each other, a process that can significantly alter their appearance and properties. ​ The study of galaxies, their formation, and their evolution is a central focus of modern astrophysics and cosmology. Terrestrial Planets The four innermost planets in our solar system are known as the terrestrial planets: ​ Mercury: The smallest and closest planet to the Sun, with a rocky, cratered surface. ​ Venus: The second planet from the Sun, with a thick, toxic atmosphere and a surface temperature hot enough to melt lead. ​ Earth: The third planet from the Sun, the only known planet to harbor life, with a diverse range of ecosystems. ​ Mars: The fourth planet from the Sun, often called the "Red Planet" due to its reddish appearance, with a thin atmosphere and a surface covered in craters, volcanoes, and canyons. These planets are called "terrestrial" because they have solid, rocky surfaces, unlike the gas giants (Jupiter, Saturn, Uranus, and Neptune) in the outer solar system. Lunar Eclipse Conditions A lunar eclipse occurs when the Moon passes through the Earth's shadow. This can only happen during a full moon, when the Moon is on the opposite side of the Earth from the Sun. The conditions for a lunar eclipse are: 1.​ The Moon must be in the full moon phase. 2.​ The Moon must pass through the