Honors Chemistry 1st Semester Study Guide PDF

**Honors Chemistry 1^st^ Semester Study Guide** Significant Figures - Multiplication/division: the final answer is written so that it has the same number of significant figures as the measurement with the lowest sig figs - Addition/subtraction: The final answer is written to have the...

**Honors Chemistry 1^st^ Semester Study Guide** Significant Figures - Multiplication/division: the final answer is written so that it has the same number of significant figures as the measurement with the lowest sig figs - Addition/subtraction: The final answer is written to have the same number of decimal places as the measurement, which has the fewest decimal places. - To **add significant zeros** add a decimal point and add zeros - [Significant Figures Step by Step \| How to Pass Chemistry](https://www.youtube.com/watch?v=gtwyWKnnm_I) Unit conversions - Format: given unit x one or more conversion factors = needed unit **Example Problem:** Greg\'s doctor has ordered a PET scan of his heart. In radiological imaging, dosages of pharmaceuticals are based on body mass. If Greg weighs 64 lb, what is his body mass in kg? **STEP 1:** State the given and needed quantities    Ex: lbs (US) \--\> kg (metric) **STEP 3:** State the inequalities and conversion factors Ex: 1kg = 2.205 lb Note: write the given, 164lb, and multiply by the conversion factor that has lb in the denominator to cancel the lb in the given **Using Two or More Conversion Factors:** Oftentimes, two or more conversion factors are needed to complete the change of units. In these problems, one factor follows the other. Each factor is arranged to cancel the preceding unit until the needed unit is reached. **Example Problem:** Greg has been diagnosed with diminished thyroid function. His doctor prescribes a dosage of 0.150 mg of Synthroid to be taken once a day. If the tablets in stock contain 75 mcg of Synthroid, how many tablets are required to provide the prescribed medication? **STEP 1:** State the given and needed quantities **STEP 2:** Write a plan to convert the given unit to the needed unit **STEP 3:** State the equalities and conversion factors **STEP 4:** Set up the problem to cancel units and calculate the answer Note: The problem can be set up using the metric factor to cancel milligrams, then the clinical factor to obtain the number of tablets as the final unit. A whiteboard with black text and red text Description automatically generated Density-the relationship of the mass of an object to its volume expressed as grams per cubic centimeter (g/cm3), grams per milliliter (g/mL), or grams per liter (g/L) - Every substance has a unique density, which distinguishes it from other substances - If an object is less dense than a liquid, the object floats when placed in the liquid - Density of Solids Using Volume Displacement - The volume of a solid can be determined by volume displacement, when a solid is completely submerged in water, it displaces a volume that is equal to the volume of the solid Problem-Solving Using Density - Density can be used as a conversion factor, for example, if the volume and the density of a sample are known, the mass in grams of the sample can be calculated  Practice 1. During surgery, a patient receives 3.0 pt of blood. How many kilograms of blood (density = 1.06 g/mL) were needed for the transfusion? 2. A woman receives 1280 g of type A blood. If the blood has a density of 1.06 g/mL, how many liters of blood did she receive? Homogeneous/Heterogeneous Mixtures: - Homogenous Mixture: Matter that consists of just one type of atom or one type of molecule. - Heterogenous Mixture: The components do not have a uniform composition throughout the sample. **Classify A-C as a pure substance (element or compound) or a mixture (homogeneous or heterogeneous).** A. Copper in wire B. Chocolate-chip ice cream C. Nitrox (A combination of oxygen and nitrogen used to fill scuba tanks) A. A salad dressing is prepared with oil, vinegar, and chunks of blue cheese. Is this a homogeneous or heterogeneous mixture? A. A mouthwash is used to reduce plaque and clean gums. It contains several ingredients, such as menthol, alcohol, hydrogen peroxide, and flavoring. Is this a homogeneous mixture or a heterogeneous mixture? Physical & Chemical Changes - Physical change- the physical properties of a substance change, but its identity stays the same - Ex: boiling water, melting ice, freezing water, and dissolving salt in water - Chemical change- characteristics that indicate the ability of a substance to change into a new substance - Ex: burning wood, cooking food, rusting of iron, digestion of food, baking a cake, souring milk, boiling an egg, photosynthesis, fireworks exploding, and the color change in leaves during autumn States of Matter- solid, liquid, and gas - Solid- particles are tightly packed together, resulting in definite shape and volume - Liquid- flows freely, takes the shape of its container but retains nearly constant volume - Gas- particles are widely spread, move in random directions, and have neither definite shape nor volume Atomic Theory- the scientific theory that matter is composed of particles called atoms. The definition of the word \"atom\" has changed over the years in response to scientific discoveries +-----------------------+-----------------------+-----------------------+ | **Scientist** | **What They | **Model of Atom** | | | Contributed + | | | | Evidence** | | +=======================+=======================+=======================+ | **Dalton** | 1. John Dalton\'s | A black circle with | | | atomic theory, | white border | | **1803** | proposed in the | Description | | | early 1800s, was | automatically | |   | groundbreaking | generated | | | and laid the | | |   | foundation for |   | | | modern chemistry, | | | | even though some | | | | aspects were | | | | later refined | | | | with advancements | | | | in scientific | | | | knowledge. | | | | (ChatGPT) | | | | | | | |   | | | | | | | | 1. He proposed the 5 | | | | Postulates of an | | | | atom, which | | | | include: | | | | (ChatGPT) | | | | | | | | - All matter is | | | | composed of | | | | tiny, | | | | indivisible | | | | particles | | | | called | | | | atoms .  | | | | | | | | - Atoms of the | | | | same element | | | | are identical | | | | in mass and | | | | properties, | | | | but atoms of | | | | different | | | | elements have | | | | different | | | | masses and | | | | properties .  | | | | | | | | - Atoms cannot | | | | be created or | | | | destroyed in | | | | a chemical | | | | reaction .  | | | | | | | | - Compounds are | | | | formed when | | | | atoms of | | | | different | | | | elements | | | | combine in | | | | simple, | | | | whole-number | | | | ratios .  | | | | | | | | - Chemical | | | | reactions | | | | involve the | | | | rearrangement | | | | of atoms, not | | | | their | | | | creation or | | | | destruction  | | +-----------------------+-----------------------+-----------------------+ | **Thomson** | 1. He discovered the |   | | | electron. First | | | **1897** | subatomic |   | | | particle | | |   | discovered. He |   | | | used a cathode | | |   | ray tube. The |  | | | was a negative | | | | | | | |   | | | | | | | | 1. Also, he proposed | | | | the plum pudding | | | | model, suggesting | | | | that atoms are | | | | composed of a | | | | positively | | | | charged \"soup\" | | | | in which | | | | negatively | | | | charged electrons | | | | are embedded like | | | | plums in a | | | | pudding | | | | | | | |   | | | | | | | | 1. Thomson measured | | | | the electron\'s | | | | charge-to-mass | | | | ratio, providing | | | | information about | | | | its properties | | | | and helping to | | | | make the | | | | existence of | | | | subatomic | | | | particles. | | | | (ChatGPT) | | +-----------------------+-----------------------+-----------------------+ | **Rutherford** | He discovered the |   | | | nucleus of the atom. | | | **1911** | It\'s a positively |   | | | charged cloud with | | |   | electrons. |   | | | | | |   |   |   | | | | | | | Gold Foil Experiment: | Rutherford Atomic | | | He directed alpha | Model Observations | | | particles at a thin | and Limitations In | | | gold foil. He | Detail | | | observed that while | | | | most particles passed | | | | through, some were | | | | deflected at large | | | | angles. This led him | | | | to conclude that | | | | atoms have a small, | | | | dense nucleus at | | | | their center. | | | | | | | |   | | | | | | | | He proposed the | | | | nuclear model of the | | | | atom, in which most | | | | of the atom\'s mass | | | | and positive charge | | | | are concentrated in | | | | the nucleus, with | | | | electrons orbiting | | | | around it. This model | | | | was changed from | | | | Thomson\'s \"plum | | | | pudding model.\" This | | | | shifted the research | | | | more to the nucleus. | | | | (History of an Atom | | | | Notes) | | +-----------------------+-----------------------+-----------------------+ | **Bohr** | 1. Neil Bohr | ![A diagram of a atom | | | contributed to | Description | | **1913** | the atomic theory | automatically | | | by proposing the | generated](media/imag | |   | \"Bohr Model\" | e8.png) | | | which stated that | | |   | electrons orbit |   | | | the nucleus in | | | | distinct, stable | | | | energy levels. | | | | The electrons can | | | | jump between | | | | these orbits when | | | | absorbing or | | | | emitting energy. | | | | (History of Atom | | | | Notes) | | | | | | | |   | | | | | | | | 1. Neil primarily | | | | used the emission | | | | spectra test, | | | | using t-he | | | | different lines | | | | to develop his | | | | theory. (History | | | | of Atom Notes) | | | | | | | |   | | +-----------------------+-----------------------+-----------------------+ Isotopes- atoms of the same element have the same number of protons but different number of neutrons Atomic Emission Spectra-a spectrum of the electromagnetic radiation emitted by a source 1. The electron absorbs energy and goes to a higher energy level 2. The electron emits that energy in the form of a photon that produces a certain color and goes back down to its original energy level Electromagnetic Radiation**-** forms of energy such as visible light, microwaves, x-rays, ect. That travel as waves at the speed of light.   **Wavelength:** the distance between adjacent crests or troughs in a wave **Frequency:** the number of times the crest of a wave passes a point in 1 sec **Electromagnetic spectrum:** arrangement of types of radiation from long to short wavelengths. - The higher the frequency, the shorter the wavelength, and vis versa - The higher the frequency the stronger the energy, and that correlates to different colors being emitted - Different objects have different frequencies Highest to lowest- radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays Periodic Trends - Ionization energy- increases as you go up and to the right - Electronegativity- increases as you go up and right - Atomic radius- increase as you go down and to the left - Metallic character- increases as you go diagonally down from the most top right - Nonmetallic character- increases as you go diagonally up from the most bottom left  Properties of Periodic Groups- ionization, electronegativity, atomic radius, metallic and nonmetallic character Orbitals diagram- shows the placement of the electrons in the orbitals in order of increasing energy Electron configurations- a notation that helps to indicate the placement of the electrons of an atom in order of increasing energy - Each S orbital can contain up to 2 electrons. - Each p orbital can contain up to 6 electrons. - Each d orbital can contain up to 10 electrons. - Each f orbital can contain up to 14 electrons. **Pauli Exclusion Principle**: Each orbital can hold a maximum of two electrons, and these two electrons must have opposite spins. Remember for the s orbitals fill with both arrows before moving on, for p fill each orbital with a single arrow before adding a second to each Valence Electrons- They determine how an atom will bond with other atoms. Atoms try to get a full outer shell of electrons, which is usually 8 electrons (the \"octet rule\"). If an atom doesn't have a full outer shell, it will react with other atoms to either share or transfer electrons in order to achieve a full shell. - Hydrogen and Helium only need 2 for a full shell - Beryllium holds a max of 4 - Boron holds a max of 6 Electron Dot Diagrams (aka Lewis Dot Diagrams): - **Covalent Bonds**: In a covalent bond, atoms share electrons to achieve a full outer shell. Each shared pair of electrons is shown as a **dash** (or two dots). - In ionic bonding, one atom **loses** electrons and the other **gains** them. The atom that loses electrons becomes a **positive ion** (cation), and the atom that gains electrons becomes a **negative ion** (anion). In the diagram, you often show the loss or gain of electrons by drawing arrows or brackets around the ions. Ions- an atom or group of atoms that has an electric charge. - Ions with a positive charge are called cations. - Ions with a negative charge are called anions. Writing Formulas for Ionic Compounds:  **Write the symbol for the metal (cation) and its charge**: - Metals usually form **positive ions** (cations). - Look at the periodic table to find the metal\'s charge (its oxidation state).  **Write the symbol for the non-metal (anion) and its charge**: - Non-metals usually form **negative ions** (anions). - Anions typically have a charge equal to 8 minus their group number (e.g., Group 17 elements like chlorine form a -1 charge).  **Balance the charges**: - The total positive charge must equal the total negative charge, so the compound has a **neutral charge overall**. - If the charges don't balance, you need to use **subscripts** (small numbers) to adjust the number of cations and anions.  **Simplify the ratio**: - The subscript numbers should be the **smallest whole numbers** that balance the charges. Naming Ionic Compounds: **1. Name the Metal (Cation) First:** - **For metals that only form one type of ion**: Use the metal's **name** as is. - Example: **NaCl** → **Sodium chloride** - **For metals that can form more than one type of ion** (transition metals like iron, copper, etc.): - You need to specify the **charge** of the metal using Roman numerals in parentheses. - Example: **FeCl₂** → **Iron(II) chloride** (because iron has a charge of +2 here) - Example: **FeCl₃** → **Iron(III) chloride** (because iron has a charge of +3 here) **2. Name the Non-Metal (Anion) Second:** - **Change the non-metal\'s name** to end in **\"-ide\"** (instead of the original element name). - Example: **Cl⁻** → **Chloride**, **O²⁻** → **Oxide**, **S²⁻** → **Sulfide**. **3. Combine the Names:** - Put the cation (metal) name first and the anion (non-metal) name second. - **No need for prefixes or charges** when naming ionic compounds. The charge balance is implied Molecular Compounds- a substance formed by two or more nonmetal atoms sharing electrons through covalent bonds Naming Molecular Compounds:  **Name the first element**: - Write the name of the first nonmetal element **as it appears** on the periodic table (no changes). - If the first element has more than one atom, you'll use **prefixes** (more on that in the next step).  **Name the second element**: - Write the name of the second nonmetal element, but change its ending to **\"-ide\"** (e.g., oxygen → oxide, chlorine → chloride).  **Use prefixes** to indicate the number of atoms: - Prefixes are used to tell how many atoms of each element are in the compound. - **Note**: The prefix **\"mono-\"** is **not** used for the first element, only the second.  **Combine the names**: - Put the first element\'s name, followed by the second element\'s name (with the \"-ide\" ending) and any necessary prefixes. Molecular Shapes (VSEPR)- theory that helps us predict the **shape** of a molecule based on the number of **electron pairs** around a central atom. The basic idea is that **electron pairs** (bonding and lone pairs) will repel each other and arrange themselves as far apart as possible to minimize repulsion. **Key Concepts of VSEPR Theory:** 1. **Electron Pairs Repel Each Other**:\ Electron pairs (whether they are bonding pairs or lone pairs) repel each other and try to stay as far apart as possible around the central atom. 2. **Electron Pairs Arrange Themselves**:\ The electron pairs will spread out in a specific shape depending on how many pairs there are around the central atom. The goal is to have them as far apart as possible to minimize repulsion. 3. **Molecular Geometry**:\ The shape of the molecule is determined by the arrangement of **atoms** (not the lone pairs). Lone pairs affect the geometry but don't count as part of the shape directly. 1. **Linear** (2 electron pairs): - When there are 2 bonding pairs and no lone pairs around the central atom, the shape is linear. - Example: CO₂ (carbon dioxide) has 2 bonds, so it's a straight line. - Bond angle: 180°. 2. **Trigonal Planar** (3 electron pairs): - When there are 3 bonding pairs and no lone pairs around the central atom, the shape is trigonal planar. - Example: BF₃ (boron trifluoride) has 3 bonds, so it forms a flat triangle. - Bond angle: 120°. 3. **Tetrahedral** (4 electron pairs): - When there are 4 bonding pairs and no lone pairs around the central atom, the shape is tetrahedral. - Example: CH₄ (methane) has 4 bonds, so it forms a 3D pyramid shape. - Bond angle: 109.5°. 4. **Trigonal Bipyramidal** (5 electron pairs): - When there are 5 bonding pairs and no lone pairs around the central atom, the shape is trigonal bipyramidal. - Example: PCl₅ (phosphorus pentachloride) has 5 bonds. - Bond angles: 90° and 120°. 5. **Octahedral** (6 electron pairs): - When there are 6 bonding pairs and no lone pairs around the central atom, the shape is octahedral. - Example: SF₆ (sulfur hexafluoride) has 6 bonds. - Bond angle: 90°. 1. Water (H₂O): - Oxygen has 2 lone pairs and forms 2 bonds with hydrogen. - This results in a bent shape instead of linear, even though oxygen has 2 bonding pairs. - Bond angle: \~104.5° (less than the ideal 120° due to lone pair repulsion). 2. Ammonia (NH₃): - Nitrogen has 1 lone pair and forms 3 bonds with hydrogen. - This results in a trigonal pyramidal shape. - Bond angle: \~107° (less than the ideal 109.5° due to lone pair repulsion). 1. Electron pairs repel each other, so they spread out as much as possible. 2. The number of bonding and lone pairs around the central atom determines the molecular shape. 3. Lone pairs reduce bond angles because they take up more space. Electronegativity & Polarity: **Polarity** refers to how unevenly electrons are shared between two atoms in a bond. If the electrons are shared **unequally**, the bond is **polar**. If the electrons are shared **equally**, the bond is **nonpolar**. - **Polar covalent bond**: The electrons are shared unevenly because one atom is more electronegative than the other. - **Nonpolar covalent bond**: The electrons are shared equally because both atoms have similar electronegativity. How electronegativity affects polarity:  **Nonpolar Covalent Bond:** - If two atoms have the **same electronegativity**, they will share electrons equally, making the bond **nonpolar**. - Example: **H₂ (hydrogen molecule)** -- Both hydrogens have the same electronegativity, so the electrons are shared equally.  **Polar Covalent Bond:** - If two atoms have **different electronegativities**, the more electronegative atom will pull the electrons closer, creating a **polar bond**. The more electronegative atom becomes **slightly negative** (δ-) and the less electronegative atom becomes **slightly positive** (δ+). - Example: **H₂O (water)** -- Oxygen is more electronegative than hydrogen, so it pulls the electrons towards itself, making the oxygen side of the molecule slightly negative and the hydrogen side slightly positive. This makes the water molecule **polar**.  **Ionic Bond:** - When the difference in electronegativity is very large (greater than 2), one atom may **completely steal** electrons from the other, forming an **ionic bond**. - Example: **NaCl (sodium chloride)** -- Sodium (Na) gives up an electron to chlorine (Cl), forming Na⁺ and Cl⁻ ions. **Polar molecules** have a positive end and a negative end (like water, H₂O), and they can dissolve other polar substances. **Nonpolar molecules** have no charge separation (like **O₂** or **N₂**), and they generally don't mix well with polar substances.