PS Exam

Pure Substance

Matter with a definite composition and distinct chemical properties (e.g., oxygen, carbon, hydrogen)

Mixture

Combination of two or more pure substances that are not chemically combined (e.g., air, milk, coffee)

Element

Substance composed of identical atoms (e.g., oxygen, carbon)

Compound

Substance composed of two or more different elements chemically combined (e.g., CO2, H2O, NaCl)

Homogeneous Mixture

Mixture with a uniform composition throughout (e.g., air, milk, coffee)

Heterogeneous Mixture

Mixture with a non-uniform composition (e.g., salad, cereal, soup)

Temperature

Measure of average kinetic energy of particles in a substance

Thermal Energy

Energy associated with the motion of particles in a substance

States of Matter

Forms of matter: solid, liquid, gas (based on particle kinetic energy)

Phase Changes

Transitions between different states of matter: freezing, melting, evaporation, condensation, deposition, sublimation

Melting Point

Temperature at which a substance changes from solid to liquid

Boiling Point

Temperature at which a substance changes from liquid to gas

Mass

Amount of matter in a substance or object (measured in grams)

Volume

Amount of space occupied by a substance or object (measured in cm3 or mL)

Density

Mass per unit volume of a substance or object (measured in g/cm3 or g/mL)

Solid

State of matter with particles closely packed together and fixed positions

Liquid

State of matter with particles close together but able to move past each other

Gas

State of matter with particles far apart and moving rapidly

Pure Substance Particle Diagram

All particles are identical and represent a single element or compound

Homogeneous Mixture Particle Diagram

Particles are evenly distributed throughout the substance

Heterogeneous Mixture Particle Diagram

Particles are clearly separated and can be of different sizes and shapes

On a heating curve, what lines will be will be States of Matter and what will be Phase Changes?

States: Diagonal Lines, Phase Changes: Flat lines

Temperature is the average ____________________ energy of the substance. As temperature increases the

particles will ____________________. If particles begin to slow down, the temperature

____________________.

Kinetic, Speed up, Decrease

Density Formula

Density = Mass/Volume (measured in g/cm3 or g/mL)

Density Calculation

Example: If an object has a volume of 5.5 cm3 and a mass of 3.0 g, its density is 0.55 g/cm3

Gold Foil Experiment

Conducted by Ernest Rutherford in which alpha particles that were shot at gold foil were deflected when they hit the positive center of gold atoms. The nucleus was discovered as a result of this experiment.

Proton

Positively charged particle found in the nucleus of an atom

Neutron

Particle with no charge found in the nucleus of an atom

Electron

Negatively charged particle found in electron shells around the nucleus of an atom

Nucleus

Central part of an atom, containing protons and neutrons

Atomic Number

Number of protons in the nucleus of an atom

Mass Number

Total number of protons and neutrons in the nucleus of an atom

Isotope

Atoms of the same element with different numbers of neutrons

Ion

Atom or molecule with a net electric charge due to the loss or gain of electrons

Cation

Positively charged ion (more protons than electrons)

Anion

Negatively charged ion (more electrons than protons)

cation vs anion

Bohr Model

A model resembling planets revolving around the sun in orbits, useful in visualizing the structure of atoms.

Family/Group

Vertical column on the periodic table

Period

Horizontal row on the periodic table

Ionic Charge

Net charge of an ion, determined by the number of electrons compared to protons

Valence Electrons

Electrons in the outermost shell of an atom, determining its chemical properties

Alkali Metals

Group 1A on the periodic table with a +1 ionic charge and 1 valence electron

Halogens

Group 7A on the periodic table with a -1 ionic charge and 7 valence electrons

Noble Gases

Group 8A on the periodic table with a 0 ionic charge and 8 valence electrons

Alkali Earth Metals

Group 2A on the periodic table with a +2 ionic charge and 2 valence electrons

Metals

Elements located on the left side of the periodic table, generally shiny and good conductors of heat and electricity

Metalloids

Elements located along the staircase on the periodic table, having properties of both metals and nonmetals

Nonmetals

Elements located on the right side of the periodic table, generally poor conductors of heat and electricity

Metal vs. nonmetal properties

metal-luster, solid, malleable, good conductors, ductile

nonmetal-dull, liquid or gas or a brittle solid, poor conductors

Chemical Bond

Force of attraction between two atoms

Ionic Bond

Bond formed between a metal and a nonmetal, where electrons are transferred

Covalent Bond

Bond formed between two nonmetals, where electrons are shared

Chemical Formula

Combination of chemical symbols to represent a compound (e.g., PF3)

Ionic Compound

Compound formed by the bonding of positive and negative ions

Covalent Compound

Compound formed by the sharing of electrons between two nonmetals

Lewis Dot Diagram

Diagram showing the valence electrons of an atom using dots

Balancing Chemical Reactions

Ensuring that the number of atoms of each element is the same on both sides of a chemical equation

Law of Conservation of Mass

Matter cannot be created or destroyed, only rearranged in a chemical reaction

Chemical Reaction

Process in which one or more substances are chemically changed into new substances

Reactants

Starting materials in a chemical reaction

Products

Ending materials in a chemical reaction

Endothermic Reaction

Reaction that absorbs energy (feels cold)

Exothermic Reaction

Reaction that releases energy (feels hot)

Average Atomic Mass

Average mass of all the isotopes of an element

Energy Transfer

Transfer of energy from one substance to another

Isotope Notation

Representation of an isotope using the element symbol, atomic number, and mass number

Endothermic Examples

melting, vaporization, sublimation || boiling water & dry ice sublimating

Exothermic Examples

freezing, condensation, deposition || condensation of rain from water vapor & mixing water and strong acids or strong bases.