Chemistry Honors Finals

Symbol

Symbol

A one, two, or three letter designation for an element (Ex. Sodium is Na)

Subscript

A number written to the right and below a symbol that tells the number of atoms present in a molecule (Ex. An oxygen molecule has two oxygen atoms, O2)

Formula

Symbols and subscripts used to represent the composition of a substance (can be ionic or covalent (Ex. H2O, KCl)

Chemical Bonds

Forces that hold atoms together; protons of one atom and electrons of another are attracted

Ionic bonds

Bonds between metals and nonmetals where electrons are transferred, forming an ionic compound (a salt)

Compound

A substance composed of 2 or more elements chemically combined in definite proportions

Polyatomic Ion

A group of covalently bonded atoms possessing a charge, taking part in ionic bonding

Lewis Dot Diagram

Placing valence electrons around an element's symbol to represent bonding

Covalent bonds

Bonds between nonmetals where valence electrons are shared to achieve octets

Polarity

Measure of electron distribution within a molecule, determined by the difference in electronegativity between atoms

VSEPR

Valence Shell Electron Pair Repulsion theory determining molecular shape based on electron pairs around the central atom

Gram Formula Mass (GFM)

Sum of atomic masses of all atoms in a compound, also the mass of one mole of that compound

Percent Composition

Mass percentage of an element in a compound

Empirical Formula

Simplest whole number ratio of elements in a compound

Molecular formula

Actual ratio of elements in a compound

Mole

Unit representing 6.02 × 10^23 atoms or molecules, and 1 mole of gas occupies 22.4 L at STP

Kinetic Molecular Theory (KMT)

Describes gas particles in random, straight line motion with elastic collisions.

Gas Particles

Gas particles are separated by large distances relative to their size, making the size of gas particles negligible.

Temperature and Kinetic Energy

Temperature is a measure of the average kinetic energy of gas particles; higher temperature indicates faster-moving particles.

Pressure

Pressure in a gas results from collisions of particles with each other and the walls of the container.

Gas Variables

Pressure (P), Volume (V), Temperature (T), and Amount of gas (n) are key variables in gas behavior.

Gas Constant (R)

The gas constant value depends on the units used for pressure in the ideal gas law equations.

Boyle’s Law

Describes the inverse relationship between pressure and volume in a gas, P1V1 = P2V2.

Charles’ Law

States the direct relationship between temperature and volume in a gas, V1/T1 = V2/T2.

Avogadro’s Law

Shows the direct relationship between the number of moles and volume of a gas, n1/V1 = n2/V2.

Solution

A homogeneous mixture where solute dissolves in a solvent, forming a clear mixture that does not disperse light.

Solute and Solvent

The solute is the substance being dissolved, while the solvent is the substance doing the dissolving in a solution.

Unsaturated

Less solute dissolved than the maximum

Saturated

Maximum amount of solute dissolved, no more solute can dissolve

Supersaturated

More solute is dissolved than the solute can technically handle at that temperature (very unstable, have to heat up first and then cool slowly to create this type)

Filtration

Separates heterogeneous mixtures by filtering out larger solid particles

Heterogeneous mixture

You can see the different substances (Ex. sand in water)

Distillation

Separates liquid homogeneous solutions by differences in boiling point

Chromatography

Separates homogeneous mixtures using differences in polarity

Dilution Formula

M₁V₁ = M₂V₂

Acids

Have sour taste, electrolytes, react with metals to form H2 gas

Arrhenius Classification

Acids release H+ ions in water, bases release OH- ions in water

Bronsted-Lowry Classification

Defines acids as proton (H+) donors and bases as proton (H+) acceptors.

Hydronium

A positively charged ion formed when a water molecule gains a hydrogen ion, represented as H3O+.

Find pH from H+ concentration

-log[H⁺]

Find H+ concentration from pH

[H⁺] = 10^-pH

Neutralization Reaction

Acid + Base → Salt + H2O

Salt

any ionic compound (Ex. NaCl, KBr, KCl, MgI₂, etc.)

Titration

M_AV_A = M_BV_B

Conjugate acid base pairs

A conjugate base is whats left after an acid donates a proton.