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Questions and Answers
What is true about particles in a solid compared to those in a gas?
What is true about particles in a solid compared to those in a gas?
Which statement differentiates a homogeneous mixture from a heterogeneous mixture?
Which statement differentiates a homogeneous mixture from a heterogeneous mixture?
Which of the following is an example of a pure substance?
Which of the following is an example of a pure substance?
In what way do molecules differ from elements?
In what way do molecules differ from elements?
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What characterizes a chemical change?
What characterizes a chemical change?
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Which of the following is a characteristic of the particle model of matter?
Which of the following is a characteristic of the particle model of matter?
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How is a solution defined in relation to a mechanical mixture?
How is a solution defined in relation to a mechanical mixture?
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What distinguishes a pure substance from a pure element?
What distinguishes a pure substance from a pure element?
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What type of chemical reaction is represented by the equation $2H2(g) + O2(g) → 2H2O(l)$?
What type of chemical reaction is represented by the equation $2H2(g) + O2(g) → 2H2O(l)$?
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Which of the following describes an endothermic reaction?
Which of the following describes an endothermic reaction?
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What product forms when silver reacts with bromine?
What product forms when silver reacts with bromine?
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Which factor would NOT speed up a chemical reaction?
Which factor would NOT speed up a chemical reaction?
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What is the primary difference between an exothermic and endothermic reaction?
What is the primary difference between an exothermic and endothermic reaction?
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What type of reaction is shown by $Zn(s) + CuSO4(aq) → ZnSO4(aq) + Cu(s)$?
What type of reaction is shown by $Zn(s) + CuSO4(aq) → ZnSO4(aq) + Cu(s)$?
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Given the reaction $NaCl(aq) + AgNO3(aq) → NaNO3(aq) + AgCl(s)$, what type of reaction is it?
Given the reaction $NaCl(aq) + AgNO3(aq) → NaNO3(aq) + AgCl(s)$, what type of reaction is it?
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Which of the following compounds is classified as ionic?
Which of the following compounds is classified as ionic?
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What condition would increase the rate of a reaction in a beaker?
What condition would increase the rate of a reaction in a beaker?
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Which of the following compounds represents a molecular compound?
Which of the following compounds represents a molecular compound?
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Which of the following is an example of a chemical property?
Which of the following is an example of a chemical property?
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What is the main distinction between a law and a theory in scientific terms?
What is the main distinction between a law and a theory in scientific terms?
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In the context of atomic models, who proposed that electrons exist in fixed pathways around the nucleus?
In the context of atomic models, who proposed that electrons exist in fixed pathways around the nucleus?
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What does the atomic number of an element indicate about a neutral atom of that element?
What does the atomic number of an element indicate about a neutral atom of that element?
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Which group of elements is known to exhibit the highest reactivity?
Which group of elements is known to exhibit the highest reactivity?
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Which characteristic is NOT true about metals?
Which characteristic is NOT true about metals?
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What is the difference between ionic and molecular compounds?
What is the difference between ionic and molecular compounds?
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How are molecular compounds named differently from ionic compounds?
How are molecular compounds named differently from ionic compounds?
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What is the primary characteristic of the electron cloud model?
What is the primary characteristic of the electron cloud model?
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What type of bond typically forms in molecular compounds?
What type of bond typically forms in molecular compounds?
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When considering properties of elements, which of the following are typically found in non-metals?
When considering properties of elements, which of the following are typically found in non-metals?
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What is the role of the nucleus in an atom?
What is the role of the nucleus in an atom?
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What is the state of matter for the compound Fe2O3?
What is the state of matter for the compound Fe2O3?
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A neutral atom of fluorine differs from a fluoride ion with a -1 charge because:
A neutral atom of fluorine differs from a fluoride ion with a -1 charge because:
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Study Notes
Particle Model of Matter
- All matter is composed of extremely tiny particles (atoms).
- There are spaces between these particles.
- Particles attract each other.
- Particles are constantly moving.
- Particles move faster and farther apart when energy is added.
Atom, Element, and Molecule
- Atoms are the fundamental building blocks of all matter.
- Elements are types of atoms.
- Molecules are combinations of atoms.
Differences Among States of Matter
- Solids: Particles are tightly packed, have low energy, little movement, and are close together.
- Gases: Particles are widely spaced, have high energy, move rapidly, and are far apart.
Pure Substances, Solutions, and Mechanical Mixtures
- Pure substance: Contains only one type of particle (e.g., gold bar, water).
- Mixture: Contains two or more different types of particles (e.g., chocolate chip cookie, salad).
- Solution (homogeneous mixture): Particles are uniformly distributed (e.g., wine, coffee, blood).
- Mechanical mixture (heterogeneous mixture): Particles are not uniformly distributed (e.g., pizza, sandwich, granite).
Pure Substance vs. Pure Element
- A pure substance can be an element or a compound.
- A pure element is a substance composed of only one type of atom.
Physical and Chemical Changes
- Physical change: Changes the form (e.g., shape, size, state) but not the chemical identity of a substance.
- Chemical change: Changes the chemical composition, resulting in new substances.
| PHYSICAL CHANGE | CHEMICAL CHANGE |
|---|---|
| Changes in form (shape, size, state) but not its chemical identity | Changes the chemical composition, resulting in the formation of new substances |
| No new substance formed | New substance formed |
| Reversible | Irreversible |
Evidence of Chemical Reactions
- Heat produced or absorbed
- Change in pH
- Gas bubbles form in a liquid
- Change in color
- Reactants are used up
- Precipitate forms in a liquid
Physical and Chemical Properties
| Property | Type |
|---|---|
| Reacts with oxygen | Chemical |
| Highly malleable | Physical |
| Not soluble in water | Physical |
| pH of 4.0 | Chemical |
| Conducts electricity | Physical |
| Yellow in color | Physical |
| Extremely toxic | Chemical |
| Low density | Physical |
Laws vs. Theories
- Laws describe what happens (observations).
- Theories explain why something happens.
Atomic Models
- Thomson's "Plum Pudding" Model: Atoms are a positively charged mass with negatively charged electrons embedded in it.
- Rutherford's "Planetary" Model: Most of the atom's mass is concentrated in a central nucleus.
- Bohr's Atomic Model: Electrons orbit the nucleus in fixed pathways (energy levels).
- Electron Cloud Model: Electrons behave like waves, and their exact location cannot be precisely determined; probability distributions describe regions of likely electron location.
Elements and Atoms
- An element is a pure substance composed of one type of atom, examples are oxygen, gold, hydrogen.
Components of an Atom
- Proton: Positive charge, found in the nucleus.
- Neutron: Neutral charge, found in the nucleus.
- Electron: Negative charge, orbits the nucleus.
Atomic Number and Mass
- Atomic number equals the number of protons and electrons in a neutral atom.
- Atomic mass is the sum of protons and neutrons.
Fluorine Atom
- Fluorine has 9 protons and 9 electrons.
Fluorine Atom vs. Fluoride Ion
- Fluoride has gained an electron and carries a -1 charge, fluorine has 9 protons and 7 electrons.
Periodic Table
- Dmitri Mendeleev developed the periodic table by arranging elements in order of increasing atomic number.
Reactivity of Elements
- Most reactive: Metals and nonmetals.
- Least reactive: noble gases.
Properties of Elements
| Property | Metals | Nonmetals | Metalloids |
|---|---|---|---|
| State at room temp. | Solid (except Hg) | Various (solid, liquid, gas) | Solid |
| Appearance | Shiny lustre | Often dull | Can be shiny or dull |
| Conductivity | Good conductors of heat and electricity | Poor conductors of heat and electricity | May conduct electricity, usually poor conductors of heat |
| Malleability and ductility | Malleable and ductile | Brittle, not ductile | Brittle, not ductile |
Compound Formulas
- H₂O(g): Hydrogen, oxygen. 3 atoms
- CO₂(g): Carbon, oxygen. 3 atoms
- Fe₂O₃(s): Iron, oxygen. 5 atoms
- HCl(l): Hydrogen, chlorine. 2 atoms
Ionic vs. Molecular Compounds
- Ionic: Metal and nonmetal bonded via ionic bonds.
- Molecular: Nonmetal and nonmetal bonded via covalent bonds.
Compound Naming
- Molecular compounds use prefixes (mono, di, tri).
- Ionic compounds use cation and anion names.
Chemical Equations
- Reactants: Substances that react.
- Products: Substances formed from a reaction.
Examples of Chemical Reactions
- Formation: Two or more reactants combine to form one product.
- Decomposition: One compound breaks down into two or more simpler substances.
- Single replacement: One element replaces another element in a compound.
- Double replacement: The cations and anions of two compounds swap places.
- Combustion: A substance reacts with oxygen, releasing energy.
Reaction Rates
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Factors affecting reaction rate: Heat, stirring, reactant concentration, surface area, catalyst.
-
Catalyst: A substance that speeds up a reaction without being consumed.
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Description
Test your knowledge on the particle model of matter, including the composition of matter, states of matter, and the differences between atoms, elements, and molecules. This quiz will also explore pure substances, solutions, and mechanical mixtures.
