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Questions and Answers
Which of the following statements about atoms is correct?
Which of the following statements about atoms is correct?
What distinguishes a homogeneous mixture from a heterogeneous mixture?
What distinguishes a homogeneous mixture from a heterogeneous mixture?
When the energy of particles in a solid increases, what happens?
When the energy of particles in a solid increases, what happens?
Which of the following is an example of a pure substance?
Which of the following is an example of a pure substance?
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How do the particles in a gas differ from those in a solid?
How do the particles in a gas differ from those in a solid?
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What happens during a chemical change?
What happens during a chemical change?
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Which is true about a pure element?
Which is true about a pure element?
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Which statement best describes the characteristics of a mixture?
Which statement best describes the characteristics of a mixture?
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What type of reaction occurs when solid silver reacts with liquid bromine?
What type of reaction occurs when solid silver reacts with liquid bromine?
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Which of the following is an example of an endothermic reaction?
Which of the following is an example of an endothermic reaction?
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What is the product of the reaction between vinegar and baking soda?
What is the product of the reaction between vinegar and baking soda?
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Which equation represents a combustion reaction?
Which equation represents a combustion reaction?
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How can the rate of a reaction be increased?
How can the rate of a reaction be increased?
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Which compound is incorrectly matched with its type?
Which compound is incorrectly matched with its type?
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What type of reaction is characterized by one element replacing another in a compound?
What type of reaction is characterized by one element replacing another in a compound?
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Which of the following definitions matches a double replacement reaction?
Which of the following definitions matches a double replacement reaction?
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In which type of reaction does energy typically get released?
In which type of reaction does energy typically get released?
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What kind of product is formed in the reaction of magnesium with hydrogen ions?
What kind of product is formed in the reaction of magnesium with hydrogen ions?
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Which of the following is NOT considered evidence of a chemical reaction?
Which of the following is NOT considered evidence of a chemical reaction?
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What describes the atomic model created by Rutherford?
What describes the atomic model created by Rutherford?
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How many protons are found in a neutral atom of fluorine?
How many protons are found in a neutral atom of fluorine?
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Which of the following elements is considered a gas at room temperature?
Which of the following elements is considered a gas at room temperature?
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In terms of chemical bonding, what distinguishes ionic compounds?
In terms of chemical bonding, what distinguishes ionic compounds?
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What does an atomic number represent in a neutral atom?
What does an atomic number represent in a neutral atom?
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Which statement accurately describes a physical property?
Which statement accurately describes a physical property?
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What defines a molecular compound compared to an ionic compound?
What defines a molecular compound compared to an ionic compound?
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Which group of elements is least reactive?
Which group of elements is least reactive?
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What is the key distinguishing characteristic of Thomson's 'Plum Pudding' model?
What is the key distinguishing characteristic of Thomson's 'Plum Pudding' model?
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What characteristic does the electron cloud model emphasize about electron behavior?
What characteristic does the electron cloud model emphasize about electron behavior?
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How would the name of the compound CO2 be written?
How would the name of the compound CO2 be written?
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Which of the following describes the physical state of Fe2O3?
Which of the following describes the physical state of Fe2O3?
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What is the primary reason for the arrangement of elements in the periodic table?
What is the primary reason for the arrangement of elements in the periodic table?
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Study Notes
Particle Model of Matter
- All matter is composed of extremely tiny particles called atoms.
- There are spaces between these particles.
- Particles are attracted to one another.
- Particles are always moving.
- Particles move faster and further apart when they gain energy.
Atom, Element, and Molecule
- Atoms are the fundamental building blocks of all matter.
- Elements are types of atoms.
- Molecules are combinations of atoms.
Solid vs. Gas Particles
- Energy: Solids have less kinetic energy than gases.
- Space: Particles in solids are closer together than those in gases.
- Movement: Particles in solids vibrate in place, while particles in gases move freely.
Pure Substances, Solutions, and Mechanical Mixtures
- Pure Substance: Contains only one type of particle. Examples: Gold bar, water.
- Mixture: Contains two or more different types of particles. Examples: Chocolate chip cookie, salad.
- Solution (Homogeneous Mixture): Particles are uniformly distributed. Examples: Wine, coffee, blood.
- Mechanical Mixture (Heterogeneous Mixture): Particles are not uniformly distributed. Examples: Pizza, sandwich, chocolate chip cookie.
Pure Substance vs. Pure Element
- A pure substance can be an element or a compound.
- A pure element is a substance made up of only one type of atom.
Classifying Substances
- Distilled water: Pure substance.
- Granite: Mechanical mixture.
- Apple juice: Solution.
Physical vs. Chemical Change
- Physical Change: Alters the form (shape, size, state) but not the chemical identity. No new substances are formed. Example: Ice melting.
- Chemical Change: Alters the chemical composition, forming new substances. Example: Vanilla cake baking.
- Physical Change: Reversible.
- Chemical Change: Not reversible.
Evidence of Chemical Reactions
- Heat produced or absorbed.
- Change in pH.
- Gas bubbles form in a liquid.
- Change in color.
- Reactants used up.
- Precipitate (solid) forms in a liquid.
Physical and Chemical Properties
- Reacts with oxygen: Chemical property.
- Highly malleable: Physical property.
- Not soluble in water: Physical property.
- pH of 4.0: Chemical property
- Conducts electricity: Physical property.
- Yellow in color: Physical property.
- Extremely toxic: Chemical property.
- Low density: Physical property.
Law vs. Theory
- Law: Describes an observation (what happens).
- Theory: Explains why something happens.
Atomic Models
- Thomson's "Plum Pudding": Atoms are a positively charged mass with negatively charged particles (electrons) embedded in it.
- Rutherford's "Planetary": Almost all of an atom's mass is concentrated in its center (nucleus).
- Bohr's Atomic Model: Electrons revolve around the nucleus in fixed pathways (energy levels/shells).
- Electron Cloud Model: Electrons behave like waves, and their location is predicted mathematically.
Element Definition
- An element is a pure substance made up of one type of atom. Examples: Oxygen, gold, hydrogen.
Atomic Components
- Proton: Positively charged particle in the nucleus.
- Neutron: Neutral particle in the nucleus.
- Electron: Negatively charged particle orbiting the nucleus.
Atomic Number and Mass
- Atomic number = number of protons (and electrons in a neutral atom).
- Atomic mass = number of protons + number of neutrons.
Fluorine Atom
- Fluorine (F) has 9 protons and 9 electrons in a neutral atom. (Use periodic table.)
Fluorine vs. Fluoride Ion
- A fluorine atom has 9 protons and 9 electrons.
- A fluoride ion (F⁻) has 9 protons and 10 electrons (it gained an electron).
Periodic Table
- Dmitri Mendeleev first developed the periodic table. Arranging elements by increasing atomic number.
Reactivity Trends
- Most reactive: Metals and nonmetals (at opposite sides of the periodic table).
- Least reactive: Noble gases (in the far right column).
Properties of Elements
- Metals: Solids, shiny, good conductors of heat and electricity, malleable and ductile.
- Nonmetals: Various states, not shiny, poor conductors, brittle.
- Metalloids: Solids, can be shiny or dull, may conduct electricity, usually poor conductors of heat, brittle.
Chemical Formulas
- H₂O (g): Hydrogen, oxygen, 3 atoms (gas).
- CO₂ (g): Carbon, oxygen, 3 atoms (gas).
- Fe₂O₃ (s): Iron, oxygen, 5 atoms (solid)..
- HCl (l): Hydrogen, chlorine, 2 atoms(liquid).
Ionic vs. Molecular Compounds
- Ionic: Formed by a metal and a nonmetal, involve ionic bonds (transfer of electrons).
- Molecular: Formed by nonmetals, involve covalent bonds (sharing of electrons).
Naming Compounds
- Molecular: Use prefixes (mono, di, tri...) for the number of atoms.
- Ionic: Cation (metal) first, anion (nonmetal) second, with appropriate charges.
Chemical Equation Examples
- Silver reacting with bromine Ag(s) + Br₂(l) → AgBr(s)
- Vinegar and baking soda reaction Reactants: vinegar and baking soda, Products: sodium acetate, water and carbon dioxide.
Endothermic vs. Exothermic Reactions
- Endothermic: Absorbs heat.
- Exothermic: Releases heat.
Chemical Reaction Types
- Formation: Two or more reactants combine to form a single product. Example: 2H₂(g) + O₂(g) → 2H₂O(l).
- Decomposition: A single compound breaks down into two or more simpler substances. Example: 2H₂O₂(l) → 2H₂O(l) + O₂(g).
- Single Replacement: One element replaces another element in a compound. Example: Zn(s) + CuSO₄(aq) → ZnSO₄(aq) + Cu(s).
- Double Replacement: Two compounds react, cations and anions swap places. Example: NaCl(aq) + AgNO₃(aq) → NaNO₃(aq) + AgCl(s).
- Combustion: A substance reacts with oxygen, releasing energy (heat and often light). Example: CH₄(g) + 2O₂(g) → CO₂(g) + 2H₂O(g) + Energy.
Reaction Rate Factors
- Increasing heat increases reaction rate.
- Stirring increases reaction rate.
- Increased reactant concentration increases reaction rate.
- Larger surface area increases reaction rate.
Catalyst
- A substance that speeds up a chemical reaction without being consumed itself.
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Description
Explore the fundamentals of the particle model of matter, including the nature of atoms, elements, and molecules. This quiz delves into the characteristics of solids and gases and differentiates between pure substances, solutions, and mixtures.
