h. chemistry - atomic radius

electron shielding

the balance between the pull of protons and valence electrons and the repulsion force from core electrons

nuclear charge

the total positive charge of a nucleus based on the protons. higher protons means a higher nuclear charge. this can be offset by electron shielding

atomic radius

the relative size of an atom

atomic radius down a group? reason?

increases; when an EL is added, it decreases the attraction between the protons and electrons and increases the strength of the electron shield

atomic radius across a period? reason?

decreases; the nuclear charge is higher, and the attraction between the protons and the valence electrons are higher

first ionization energy down a group? reason?

decreases; the larger the atom, the less attracted the electrons are to the nucleus, making it easier to remove electrons

first ionization across a period? reason?

increases; the smaller the atom, the more attracted the electrons are to the nucleus, making it harder to remove

why does second ionization energy take more energy than first ionization energy?

it’s difficult to take electrons from a positive ion and some ions behave similarly to noble gases, so they don’t react as much

electronegativity

the ability to take electrons from another atom

electronegativity down a group? reason?

decreases; the increasing EL also increases the electron shielding, which weakens its own electrons and makes it less likely to attract other electrons

electronegativity for across a period? reason?

increases; it increases protons, so it increases the nuclear charge. the attraction is stronger and is more likely to attract other electrons

why are noble gases non reactive?

they have a full set of valence electrons, so they don’t attract other electrons or react as much

ionic radius cation

becomes smaller; the same number of protons attracting less electrons makes a stronger nuclear charge. the stronger attraction pulls the electrons closer, so the ion is smaller

ionic radius anion

becomes larger; same number of protons attracting more electrons makes a weaker nuclear charge

hund’s rule

if a sublevel has more than one orbital available, the electrons will choose the empty ones first

pauli’s exclusion principle

when electrons are paired together, they will spin in opposite directions

mendeleev’s periodic table

organized based on atomic mass, grouped elements based on properties, and left blanks spaces for undiscovered elements

moseley’s periodic table

organized based on atomic number, created periodic law

periodic law

when elements are arranged by increasing atomic number, their physical and chemical properties repeat periodically. they are “related”

group 1

alkali metals

group 2

alkaline earth metals

group 3-12

transition metal

group 13-16

mixed group

group 17

halogens

group 18

noble gases

octet rule

atoms will gain, lose, or share electrons to try and get a full set of valence electrons

why is fluorine the most electronegative element?

it has the least occupied EL and has the most protons in that EL. it has the most protons with the least electron shielding

why is it harder to remove electrons from ions after their valence electrons are removed?

because they’re closer to the nucleus and the attraction is stronger