AP Chemistry Semester 1 Review

Mixtures

Mixtures

homogeneous or heterogeneous that can separate into components based on physical properties

Compounds

Pure substance that includes more than one element

Elements

Atoms or molecules bound together (on periodic table)

Homogeneous Mixtures

a mixture in which substances are evenly distributed throughout the mixture

Heterogeneous Mixtures

mixture in which the composition is not uniform throughout

Celsius to Fahrenheit

F = 1.8 (C) + 32

Fahrenheit to Celsius

C = (F - 32)/1.8

Celsius to Kelvin

K = C + 273.15

Density Equation

Density = (mass)/(volume)

Density

varies with temperature and is an identifying property

Proton

positively charged particle in the nucleus that has a mass of about 1 amu.

Electron

negatively charged particle in the outer space of the atom that has a mass of 5.486x10^-4. (Its mass is so small that most ignore it)

Neutron

no charged particle in the nucleus that has a mass of about 1 amu

Mass Number

the sum of the number of neutrons and protons in an atomic nucleus

Atomic Number

The number of protons and electrons in a stable atom.

Isotope

an atom that has the same number of protons (or the same atomic number) as other atoms of the same element do but that has a different number of neutrons

Ionic Compound

composed of positive and negative ions that are combined so that the numbers of positive and negative charges are equal. (a metal and a non-metal)

Molecular Compound

a compound made up of two non metals; sharing electrons

Naming Ionic Compounds

Metals are written 1st, non-metals last. Change the ending of non-metal to "ide" unless it is a polyatomic ion. Ignore the subscripts.

Greek Prefixes for Molecular Compounds

mono, di, tri, tetra, penta, hexa, hepta, octa, nona, deca

Naming Molecular Compounds

1. The name of the element to the left is named first

2. The name of the second element is given an -ide, unless polyatomic ion.

3. Greek prefixes should be used before both elements (Ex: dihydrogen triphosphide)

4. no "mono" for first element (Ex: carbon dioxide)

Molecule

two or more atoms held together by covalent bonds

Ion

a particle that is electrically charged (positive or negative) because it has gained or lost electrons. (protons not equal to electrons)

Anion

a negatively charged ion

Cation

a positively charged ion

Polyatomic Ions

tightly bound groups of atoms that behave as a unit and carry a charge

Naming Binary Acids

1. Take root of second element, 1A) add "-hydro" prefix to the anion 1B) add "-ic" suffix" 2) Add acid as second word (EX: hydrochloric acid)

Naming Oxyacids

former suffix "ate;" root + ic. former suffix "ite;" root + ous. "i ATE ICky food at the whITE hOUSe." (EX: Perchlorate -> HCIO4: perchloric acid)

Molecular Equations

A reaction equation which shows all soluble compunds in their ionic forms, a chemical equation written using the complete formulas of reactants and products (aka the original equation)

Complete Ionic Equation

a reaction equation that shows all soluble compounds in their ionic forms (aka: it shows NaCl as Na+ and Cl−)

Net Ionic Equation

an equation that includes only those compounds and ions that undergo a chemical change in a reaction in an aqueous solution (aka: removing ions that are on both sides of the equation)

Neutralization Reaction

a chemical reaction in which an acid and a base interact with the formation of a salt and water (EX: HCl + NaOH --> NaCl (aka: the salt) + H2O (aka: water))

Gas Forming Reactions

occur through the formation of a gas and water because both products remove ions from the solution; include carbonate, sulfite, Sulfide (all are polyatomic) and NH4OH (but last one is not as common).

Synthesis (Combination) Reactions

two or more substances combine to form a more complex substance (A+B -> AB)

Decomposition Reactions

complex substances are broken up into simpler substances (AB -> A+B)

Combustion Reaction

a substance (most often a hydrocarbon) combines with oxygen, producing carbon dioxide and water

Precipitation Reaction

a reaction in which an insoluble substance forms and separates from the solution by combining two soluble substances.

Solubility Rules

1. Soluble Compounds - Anions if a compound contains one of the following Anions, they will be soluble: •Acetates •Chlorates •Perchlorates •Nitrates •Nitrites •Permanganates

Solubility Rules (cont.)

2. Soluble Compounds - Cations if a compound contains one of the following Cations, it will be soluble. •NH4 (positive charge of 1) and Almost all of the Group 1A alkali Cations

Solubility Rules (cont..)

3. Soluble Compounds with EXCEPTIONS If a compound contains one of the following Anions, they will be soluble: ------Chlorides, Bromides, Iodides {Except those compounds of Ag (+1), Hg2 (+2), and Pb (+2)} ------Sulfates {Except those compounds of Sr (2+), Ba (2+), Hg2 (2+), and Pb (2+)

Solubility Rules (cont...)

4. Insoluble Compounds with EXCEPTIONS If a compound contains one of the following Anions, they will be insoluble: ------Carbonates, Phosphates, Sulfites {Except those compounds of NH4 (+), and alkali metals cations} ------Hydroxides, Sulfides {Except those compounds of NH4 (1+), alkali metals, and Ca (2+), Sr (2+), and Ba (2+)}

Oxidation Reaction

a chemical reaction in which a reactant loses one or more electrons such that the reactant becomes more positive in charge

Reduction Reaction

a reactant gains one or more electrons, thus becoming more negative in charge

Energy

the ability to do Work or transfer heat

Work

energy used to cause an object that has mass to move

Heat

Energy used to cause the temperature of an object to rise

Potential Energy

energy stored due to an object's position or arrangement

Kinetic Energy

the energy an object has due to its motion

System

molecules chemist want to study

Surroundings

everything other than the system

Relationship of Energy to Work and Heat

Energy = heat + work

endothermic

describes a process in which heat is absorbed from the surroundings

Exothermic

describes a process in which heat is released to the surroundings

Enthalpy

(thermodynamics) a thermodynamic quantity equal to the internal energy of a system plus the product of its volume and pressure

Exergonic

chemical reaction that releases some form of energy, such as heat.

Endergonic

A chemical reaction that requires the input of energy in order to proceed.

Pauli Exclusion Principle

no two electrons or protons or neutrons in a given system can be in states characterized by the same set of quantum numbers

Hund's Rule

orbitals of equal energy are each occupied by one electron before any orbital is occupied by a second electron, and all electrons in singly occupied orbitals must have the same spin

Exceptions to Hund's Rule

Chromium ([Ar] 4s1 3d5) Copper ([Ar] 4s1 3d10) molybdenum ([Kr] 5s1 4d5) Silver ([Kr] 5s1 4d10) Gold ([Xe] 6s1 4f14 5d10)

Atomic Radius Trend

Across a period: decreases. Down a group: increases

Ionization Energy Trend

decreases from top to bottom in a group; increases from left to right in a period EXCEPTIONS: 2A-3A; 5A-6A

Electron Affinity Trend

increases going across because atoms are stable enough to hold onto their own electrons and take others from other atoms. decreases going down because size of orbitals increase making the atoms unstable EXCEPTIONS: 1A-2A; 4A-5A

Metallic Trend

increases down a group, decreases across a period

Ionization Energy

the amount of energy required to remove an electron from an atom

Electron Affinity

the energy needed to remove an electron from a negative ion to form a neutral atom or molecule

Isoelectronic series

a group of ions all containing the same number of electrons Ex: Li(+), Be(2+), N(3-), O(2-), F(-))

Lattice energy

the energy required to separate one mole of the ions of an ionic compound; q1q2/d

Electronegativity

(chemistry) the tendency of an atom or radical to attract electrons in the formation of an ionic bond

Electronegativity Trend

decreases from top to bottom in a group; increases from left to right in a period

VSEPR theory

a theory that predicts some molecular shapes based on the idea that pairs of valence electrons surrounding an atom repel each other.

Linear

2 electron domains, no lone pairs. Bond angles: 180 degrees (hybridizations: sp)

Trigonal planar

3 electron domains; no lone pairs. Bond Angles: 120 degrees (hybridizations: sp2)

Bent (aka: trigonal planar - bent)

3 electron domains; 1 lone pair. Bond angles: less than 120 degrees (hybridizations: sp3)

Tetrahedral

4 electron domains; no lone pairs. Bond angles: 109.5 degrees (hybridizations: sp3)

Trigonal pyramidal

4 electron domains; 1 lone pair. Bond angles: less than 109.5 degrees (hybridizations: sp3)

Bent (aka: tetrahedral - bent)

4 electrol domains; 2 lone pairs. Bond angles: less than 109.5 degrees (hybridizations: sp3)

Trigonal bipyramidal

5 electron domains; no lone pairs. Bond angles: 90 and 120 degrees (hybridizations: sp3d)

Seesaw

5 electron domains; 1 lone pair. Bond angles: 90 and 120 degrees (hybridizations: sp3d)

T-shaped

5 electron domains; 2 lone pairs. Bond angles: 90 degrees (hybridizations: sp3d)

Linear (aka: trigonal bipyramidal - linear)

5 electron domains; 3 lone pairs. Bond angles: 180 degrees (hybridizations: sp3d)

Octrahedral

6 electron domains; no lone pairs. Bond angles: 90 degrees (hybridizations: sp3d2)

Square Pyramidal

6 electron domains; 1 lone pair. Bond angles: 90 degrees (hybridizations: sp3d2)

Square Planar

6 electron domains; 2 lone pairs. Bond angles: 90 degrees (hybridizations: sp3d2)

Sigma bonds

single covalent bonds; there is always ONE in any bond (either it be single, double, or triple)

Pi bonds

Side to side overlap of orbitals; this is in double and triple bonds. Double bonds have one sigma and one pi bond. Triple bonds have one sigma and two pi bonds.

Molar Volume of a gas at STP

22.4 L

Conditions of STP

273 K or 0 C, 1 atm

Conditions of real gases

low temperature, high pressure

Condition of ideal gases

high temperature, low pressure

Kinetic Molecular Theory

the theory that all matter is composed of particles (atoms and molecules) moving constantly in random directions

Polarizability

the ease with which the electron distribution in the atom or molecule can be distorted

London-disperson forces

A temporary attractive force that results when the electrons in two adjacent atoms occupy positions that make the atoms form temporary dipoles.

Dipole-dipole

created by equal but opposite charges that are separated by a short distance

Hydrogen Bonding

The intermolecular force in which a hydrogen atom that is bonded to a highly electronegative atom (Fluorine, Oxygen, and Nitogen) is attracted to an unshared pair of electrons of an electronegative atom in a nearby molecule.

Intermolecular Interactions affecting Boiling/ Melting Points

The higher the intermolecular force, the higher the boiling and melting points

Intermolecular Interactions affecting Bond Strength

The higher the intermolecular force, the stronger the bond.

alpha particle

a positively charged particle that is the nucleus of the helium atom; affects mass number by 4 and atomic number by 2.

beta particle

affects atomic number by increasing by 1; this emission is helping when higher than belt of stability

gamma particle

no charge; , High energy that only lead and concrete can stop

Phase Diagrams

a graph of pressure versus temperature that shows in which phase a substance exists under different conditions of temperature and pressure