Physical Science S2 Exam Study Guide Notes
Ch. 14 States of Matter
What is a state of matter? Define the four major ones discussed in class.
A state of matter is a distinct form that matter can take. The four major states of matter are solid, liquid, gas, and plasma.
What is the kinetic theory of matter? What does it say?
The kinetic theory of matter states that all matter is composed of particles (atoms, ions, or molecules) in continuous motion. The speed of these particles is proportional to temperature. Specifically:
All matter is made of atoms and molecules that act like tiny particles.
These particles are always in motion. The higher the temperature, the faster they move.
At the same temperature, more massive (heavier) particles move slower than less massive (lighter) particles.
What is a phase change? List six common examples.
A phase change is a physical process where a substance transitions from one state of matter to another. Six common examples include:
Melting (solid to liquid)
Freezing (liquid to solid)
Boiling/Vaporization (liquid to gas)
Condensation (gas to liquid)
Sublimation (solid to gas)
Deposition (gas to solid)
What is an endothermic change? An exothermic change?
Endothermic change: A process that absorbs heat from its surroundings. The surroundings get colder.
Exothermic change: A process that releases heat to its surroundings. The surroundings get warmer.
What is heat of fusion? Heat of vaporization?
Heat of fusion: The amount of energy required to change a substance from a solid to a liquid at its melting point.
Heat of vaporization: The amount of energy required to change a substance from a liquid to a gas at its boiling point.
Ch. 15 Properties of Matter
What are chemical properties? List some examples.
Chemical properties describe how a substance changes into a new substance. Examples include:
Flammability: Ability to burn.
Reactivity with acid: How readily a substance reacts with acid.
Oxidation: How readily a substance rusts or corrodes.
What is a chemical change? How do you know when one has occurred?
A chemical change is a process that produces new substances with different properties than the original substances. Indicators of a chemical change include:
Change in color
Formation of a precipitate (solid)
Production of a gas (bubbles)
Change in temperature (heat or light given off or absorbed)
Change in odor
How do you know if a change is chemical or physical?
Physical change: Alters the form or appearance of a substance but does not change its chemical composition (e.g., melting ice, cutting paper).
Chemical change: Results in the formation of new substances with different chemical compositions (e.g., burning wood, rusting iron).
What is a pure substance?
A pure substance is matter that has a fixed chemical composition and distinct properties. Examples include elements and compounds.
Define the two kinds of mixtures.
Homogeneous mixture: A mixture that has uniform composition throughout; its components are evenly distributed (e.g., salt water, air).
Heterogeneous mixture: A mixture that does not have uniform composition; its components are not evenly distributed (e.g., sand and water, salad).
Define: solution, suspension, colloid
Solution: A homogeneous mixture where one substance (solute) is dissolved in another (solvent) (e.g., sugar dissolved in water).
Suspension: A heterogeneous mixture containing large particles that settle out over time (e.g., muddy water).
Colloid: A mixture with particles larger than those in a solution but smaller than those in a suspension; they do not settle out (e.g., milk, fog).
What is density? What units are used when measuring density? What is the formula for density?
Density is the mass per unit volume of a substance. The units commonly used for measuring density are g/cm³ (grams per cubic centimeter) for solids and liquids, and g/L (grams per liter) for gases.
Formula for density: Density = {Mass} / {Volume}
or D = M/V
Discuss the 6 physical properties we talked about in class.
Color: The visual appearance of a substance.
Odor: The smell of a substance.
Mass: The amount of matter in a substance.
Volume: The amount of space a substance occupies.
Density: The mass per unit volume of a substance.
State: The physical form of a substance (solid, liquid, gas).
What is a physical change?
A physical change is a change that affects the form or appearance of a substance but does not alter its chemical composition (e.g., cutting, crushing, melting, boiling).
What is the formula for density?
Density = {Mass} / {Volume}
or D = M/V
How do you determine the volume of a regularly shaped solid?
For a regularly shaped solid, measure its dimensions (length, width, height) and use the appropriate formula to calculate its volume (e.g., volume of a cube = length x width x height).
How do you determine the volume of an irregularly shaped solid?
Use the water displacement method: Place the object in a known volume of water and measure the change in water level. The change in water level equals the volume of the object.
Ch. 16 Atomic Structure
Know your element symbols.
Memorize the symbols for common elements (e.g., H for hydrogen, O for oxygen, C for carbon, N for nitrogen, Na for sodium, Cl for chlorine).
What is the difference between an element and a compound?
Element: A pure substance consisting of only one type of atom (e.g., gold (Au), oxygen (O)).
Compound: A substance formed when two or more elements are chemically bonded together in a fixed ratio (e.g., water (H₂O), sodium chloride (NaCl)).
Who was the first person to have an idea about atoms?
Democritus, a Greek philosopher, was among the first to propose the idea of atoms as indivisible particles.
Who was the person who made the atomic theory?
John Dalton is credited with developing the first modern atomic theory.
What are the three subatomic particles that make up atoms?
Protons, neutrons, and electrons.
What is the charge of each of the subatomic particles and where are they found?
Proton: Positive charge (+1), located in the nucleus.
Neutron: No charge (neutral), located in the nucleus.
Electron: Negative charge (-1), located in orbitals surrounding the nucleus.
How do you determine the atomic mass of an element?
The atomic mass of an element is the weighted average mass of the isotopes of that element, usually expressed in atomic mass units (amu). It is found on the periodic table.
How do you determine the atomic number of an element?
The atomic number of an element is the number of protons in the nucleus of an atom of that element. It is unique to each element and is found above the element symbol on the periodic table.
How many electrons can fit in each energy level?
The number of electrons that can occupy each energy level (shell) is determined by the formula 2n^2, where n is the energy level number.
What are the electrons on the outer most energy level called?
Valence electrons.
Ch. 17 Periodic Table
What are the elements on the left hand side of the periodic table called? Right? Middle?
Left side: Metals (excluding hydrogen)
Right side: Nonmetals
Middle: Transition metals
The periodic table is in order of increasing….
Atomic number (number of protons).
Who is credited with making the periodic table?
Dmitri Mendeleev is credited with creating the first periodic table arranged by atomic mass.
Ch. 18 Chemical Bonds
What is an ion? What are the different types?
An ion is an atom or molecule that has gained or lost electrons, giving it an electrical charge.
Cation: A positively charged ion (lost electrons).
Anion: A negatively charged ion (gained electrons).
What is an ionic bond? How is it different from a covalent bond?
Ionic bond: A chemical bond formed through the electrostatic attraction between oppositely charged ions (typically between a metal and a nonmetal) (e.g., NaCl).
Covalent bond: A chemical bond formed through the sharing of electron pairs between atoms (typically between two nonmetals) (e.g., H₂O).
What is a polar molecule?
A polar molecule is a molecule with an uneven distribution of electron density, resulting in a positive end and a negative end (dipole moment) (e.g., Water).
What does the diagram N=N indicate?
It indicates a double covalent bond between two nitrogen atoms, where they share two pairs of electrons.
How do you name ionic and covalent bonds?
Ionic compounds: Name the metal first, followed by the nonmetal with the suffix "-ide" (e.g., NaCl is sodium chloride).
Covalent compounds: Use prefixes to indicate the number of atoms of each element (mono-, di-, tri-, etc.) (e.g., CO₂ is carbon dioxide).
Ch. 19 Chemical Reactions
What is oxidation and reduction?
Oxidation: Loss of electrons (increase in oxidation number).
Reduction: Gain of electrons (decrease in oxidation number).
What are the signs of a chemical reaction?
Change in color
Formation of a precipitate (solid)
Production of a gas (bubbles)
Change in temperature (heat or light given off or absorbed)
Change in odor
In a chemical equation, what are the materials on the left side of the arrow called?
Reactants.
What are the materials on the right side of the arrow called?
Products.
What does the arrow stand for?
The arrow (→) stands for "yields" or "reacts to produce."
Describe the Law of Conservation of Matter.
The Law of Conservation of Matter states that matter cannot be created or destroyed in a chemical reaction. The number of atoms of each element must be the same on both sides of the chemical equation.
How can we change the speed of a reaction?
Temperature: Increase temperature to speed up the reaction.
Concentration: Increase concentration of reactants to speed up the reaction.
Surface area: Increase surface area of solid reactants to speed up the reaction.
Catalyst: Add a catalyst to speed up the reaction.
What does (aq), (s), (l), and (g) stand for?
(aq): Aqueous (dissolved in water)
(s): Solid
(l): Liquid
(g): Gas
Describe a synthesis reaction.
A synthesis reaction is a reaction in which two or more substances combine to form a single product (A + B → AB).
Describe a decomposition reaction.
A decomposition reaction is a reaction in which a single compound breaks down into two or more simpler substances (AB → A + B).
Describe a single-replacement reaction.
A single-replacement reaction is a reaction in which one element replaces another element in a compound (A + BC → AC + B).
Describe a double-replacement reaction.
A double-replacement reaction is a reaction in which the positive ions of two compounds exchange places (AB + CD → AD + CB).
Describe the difference between an exothermic reaction and an endothermic reaction.
Exothermic reaction: A reaction that releases heat energy into the surroundings, causing the temperature of the surroundings to increase.
Endothermic reaction: A reaction that absorbs heat energy from the surroundings, causing the temperature of the surroundings to decrease.
Describe what types of energy changes occur when chemical bonds are broken or formed.
Breaking chemical bonds requires energy (endothermic process).
Forming chemical bonds releases energy (exothermic process).
Be able to balance equations.
Make sure that the number of atoms of each element is the same on both sides of the equation by adjusting the coefficients in front of the chemical formulas.
Ch. 20 Radioactivity
What does it mean to decay?
In the context of radioactivity, decay refers to the process by which an unstable atomic nucleus loses energy by emitting radiation (alpha particles, beta particles, or gamma rays).
What is the difference between nuclear fission and nuclear fusion?
Nuclear fission: The process of splitting a heavy nucleus into two or more lighter nuclei, releasing a large amount of energy.
Nuclear fusion: The process of combining two or more light nuclei to form a heavier nucleus, releasing a large amount of energy.
What is an isotope?
Isotopes are atoms of the same element that have the same number of protons but different numbers of neutrons (and thus different mass numbers).
How many neutrons does the isotope Carbon-14 have?
Carbon-14 has 6 protons (because it's carbon) and 14 - 6 = 8 neutrons.
What is a radioactive isotope called?
Radioisotope or Radioactive nuclide.
What does the term "half-life" refer to?
Half-life is the time required for one-half of the radioactive atoms in a sample to decay.
The half-life of isotope X is 4 years. How many years would it take for an 8.0 g sample of X to decay and have only .50 g of it remaining?
8. 0g -> 4.0g (1 half-life, 4 years)
9. 0g -> 2.0g (2 half-lives, 8 years)
0g -> 1.0g (3 half-lives, 12 years)
0g -> 0.50g (4 half-lives, 16 years)
It would take 16 years.
Selenium-83 has a half-life of 25.0 minutes. How many minutes would it take for a 20.0 mg sample to decay and have only 1.25 mg of it remain?
0mg -> 10.0mg (1 half-life, 25.0 minutes)
0mg -> 5.0mg (2 half-lives, 50.0 minutes)
0mg -> 2.5mg (3 half-lives, 75.0 minutes)
5mg -> 1.25mg (4 half-lives, 100.0 minutes)
It would take 100.0 minutes.