Honors Chemistry 1 - Semester 1 Final

Kelvin to Celsius Conversion

K = °C + 273

Error Calculation Formula

Error = Experimental Value - Accepted Value

Percent Error Formula

% Error = (|Error| / Accepted Value) x 100

Atomic Number (Z)

Number of protons in the nucleus (identifies the element).

Alpha Particle (α)

A helium nucleus (4/2 He); has a +2 charge and mass of 4 amu.

Beta Particle (β)

An electron emitted from the nucleus (0/-1 e); happens when a neutron turns into a proton.

Aufbau Principle

Electrons occupy the orbitals of lowest energy first.

Pauli Exclusion Principle

An atomic orbital may describe at most two electrons, and they must have opposite spins.

Hund's Rule

Electrons occupy orbitals of the same energy one at a time before pairing up.

Max Electrons in Energy Level n

2n^2 (e.g., n=3 holds 18 electrons).

Wavelength and Frequency Relationship

Inversely related (as wavelength increases, frequency decreases).

Group 1A Elements

Alkali Metals (highly reactive, 1 valence electron).

Group 2A Elements

Alkaline Earth Metals (2 valence electrons).

Group 7A Elements

Halogens (salt-formers, 7 valence electrons).

Group 8A Elements

Noble Gases (inert/non-reactive, full valence shell).

Atomic Size Trend: Down a Group

Increases (due to added energy levels/shielding).

Atomic Size Trend: Across a Period

Decreases (due to increased nuclear charge pulling electrons closer).

Electronegativity Definition

The ability of an atom to attract electrons when the atom is in a compound.

Valence Electrons

Electrons in the highest occupied energy level (determine chemical properties).

Octet Rule

Atoms react by gaining or losing electrons so as to acquire the stable electron structure of a noble gas (usually 8 valence e-).

Metallic Bond Model

"Sea of Electrons" - valence electrons are mobile and drift freely between metal cations.

VSEPR Theory

Valence-Shell Electron-Pair Repulsion theory; explains 3D molecular shapes based on electron repulsion.

Molecular Shape: CH4 (Methane)

Tetrahedral (109.5 degree bond angle).

Molecular Shape: NH3 (Ammonia)

Trigonal Pyramidal (has one lone pair).

Molecular Shape: H2O (Water)

Bent (has two lone pairs).

Molecular Shape: CO2 (Carbon Dioxide)

Linear (180 degree bond angle).

Polar Molecule

A molecule with an unequal distribution of charge (one end is slightly negative, the other slightly positive).

Naming: Transition Metals

Use Roman Numerals to indicate the charge (e.g., Iron(III) is Fe3+).

Naming: Molecular Compounds

Use prefixes (mono, di, tri, tetra, penta…) to indicate the number of atoms.

Acid Naming: Anion ends in -ide

Hydro-[stem]-ic acid (e.g., Chloride -> Hydrochloric acid).

Acid Naming: Anion ends in -ite

[Stem]-ous acid (e.g., Sulfite -> Sulfurous acid).

Acid Naming: Anion ends in -ate

[Stem]-ic acid (e.g., Nitrate -> Nitric acid).

Standard Temperature and Pressure (STP)

0°C and 1 atm (or 101.3 kPa).

Molar Mass

The mass of one mole of a pure substance (g/mol), calculated from the periodic table.

Percent Composition Formula

% mass = (mass of element / mass of compound) x 100

Resonance Structures

Structures that occur when it is possible to draw two or more valid electron dot structures for a molecule.

Network Solid

Solids in which all of the atoms are covalently bonded to each other (e.g., Diamond, SiO2); very high melting points.

Polyatomic Ion

A tightly bound group of atoms that behaves as a unit and has a positive or negative charge (e.g., SO4 2-).