Chemistry Unit 2 Vocab

Proton

A subatomic particles occurring in all atomic nuclei, has a positive charge

Neutron

A subatomic particles, has no charge (neutral)

Electron

A subatomic particles that orbits the nucleus of an atom, has a negative charge

Atomic Number

Number of protons

Mass number

p + n

Isotope

Atoms with the same number of protons and electrons, but a different number of neutrons, changing the mass but not the element

Relative Abundance

% of atoms of a specific isotope present in a naturally occurring sample of element

Avg. Atomic Mass

A weighted average of the masses of all the isotopes of an element

Ion

An atom or molecule that is charged due to a difference in the # of electrons and protons

Cation

Positively charged ion (p > e)

Anion

Negatively charged ion (p < e)

Group (on periodic table)

The columns, shows the # of valence electrons

Period (on periodic table)

The rows, show the # of rings (energy level)

Coulombic Attraction

The attraction between oppositely charged particles (p & e)

Atomic Radius

The distance from the nucleus to the outermost electron or boundary of an atom’s electron cloud

Ionization Energy

The minimum amount of energy required to remove an electron from an ion

Electronegativity

The tendency or ability of an atom to attract electrons

Reactivity

The measure of how readily a substance undergoes a chemical reaction and transforms

Nuclear Energy

Energy released from the nucleus through fission and fusion

Radioactive Decay

Unstable elements decaying into more stable elements

Alpha Decay

When an alpha particle is released during radioactive decay

Alpha Particle

⁴₂ He

Beta Minus Decay

When a beta particle is released during radioactive decay

Beta Particle

An electron (⁰_-1 e)

Gamma Decay

When an gamma particle is released during radioactive decay

Stability

A substance’s tendency to remain unchanged

Half Life

The time it takes for ½ of a substance to decay into a new substance

Neutral Atom

Has the same number of electrons and protons

Trend down a column

Coulombic attraction decreases, distance (atomic radius) increases, ionization energy decreases, electronegativity decreases

Trend across a row

Coulombic attraction increases, protons increase, less reactive, ionization energy increases, electronegativity increases