Chemistry: Unit 3

Protons

Positvely charged, located in nucleus

Nuetrons

Neutrol, located in nucleus

Electrons

Negatively charged, surround the nucleus

Atomic Number

Number of protons

Atomic mass

Protons + Neutrons

Isotope

Atoms of an element that have different numbers of nuetrons in nucleus and thus different atomic masses

Average atomic mass

Average of all isotopes of a particular element (Number is NOT rounded)

Ion

Charged atom

Cation

Less electrons, positive charged

Ionization energy down a period

Requires less energy so decreases valence electrons are farther away away from protons attracting them

Ionization energy across a period

Requires more energy so increases since electrons added in same energy level don’t sheild electrons from nuclear charge

Ionization energy

Energy required to remove one electron

Valence electrons

Electrons in the outermost energy level

Anion

More electrons, negatively charged

Atomic radius across a period

Atoms get smaller/decrease because of increased number of protons attracting electrons

Atomic radius down a group

Atoms get larger/increase because of energy levels being added to atom

Electron Affinity

Energy change when an electron is added

Electron affinity across a period

Releases more energy so number increases since electrons added don’t sheild electrons from nuclear change

Electron affinity down a group

Releases less energy so number decreases since electrons being added are farther away from attracting protons

Electronegatvity

Measure of the ability of an atom to attract electrons

Electronegativity across a period

Increases because electrons are closer to the nucleus in a small atom

Electronegativity down a group

Decreases because electrons are farther from the nucleus in a large atom

“s” sublevels

1 orbital, 2 total electrons

“p” sublevels

3 orbitals, 6 total electrons

“d” sublevels

5 orbitals, 10 total electrons

“f” sublevels

7 orbitals, 14 total electrons

Period

Row on periodic table

Group

Column on periodic table

What group doesn’t bond with others

Noble gases, has a full shell is already “happy”