GEN CHEM Ch. 2 Periodic Properties

group

elements in the same column with same number of valence electrons

period

elements in the same row with same number of electron shells

atomic number

number of protons in the atom

mass number

protons and neutrons in a nucleus

group 1

alkaline metals

• very reactive with H₂O

group 2

alkaline earth metals

• reactive with H₂O

group 3-12

transition metals

• colorful except row 4

• multiple oxidation states

  • most common (+2)

• high melting and boiling point

• valence electrons in outermost d-orbital

group 13-17

metalloids

• combination of metal and non-metal properties

group 17

halogens

group 18

noble gases

period 6-7

inner transition metals

• lanthanides (6) and actinides (7)

• multiple oxidation states

  • most common (+3)

• valence electrons in f-orbital

oxidation states

number of electrons that an atom loses, gains, or appears to use when bonding with another atom

diatomic atoms

atoms that are usually found paired due to their unstable nature

• Have No Fear Of Ice Cold Beer

  • Hydrogen, Nitrogen, Fluorine, Oxygen, Iodine, Chlorine, Bromine

metals

• malleable, lustrous

• good conductors of electricity/heat

• form basic oxides

• lose electrons to form cations

• usually solid at room temp, with exception of mercury (Hg) which is liquid

• generally high MP and BP

non-metals

• brittle, dull

• poor conductors of electricty/heat

• form acidic oxides

• gain electrons to form anions

• gas or solid at room temp, with the exception of bromine (Br) which is liquid

• general low MP and BP

atomic radius

• half the distance between the nuclei of two identical atoms between the nuclei of two identical atoms bonded = d/2

• increases from R to L across a period and increases going down a group

  • anions have larger radii compared to cations (anions have more e^- in the outer shell)

  • isoelectronic series → have the same number of e^- but a different number of protons

  • ex: Ca⁺² < K⁺¹ < Ar < Cl^- < S^-2

atomic radius increases from ___ to ___ across a period and increases going ____ a group

R to L, down

anions have larger ____ compared to cations (anions have more e^- in the outer shell)

radii

isoelectronic series

have the same number of e- but a different number of protons

• anions = ions that have gained e^- and have more e^- than protons → negatively charged

• cations = ions that have lost e^- and have more protons than e^- → positively charged

anions

ions that have gained e- and have more e- than protons → negatively charged

• larger radius

• typically for

cations

ions that have lost e- and have more protons than e- → positively charged

• smaller radius

• typically formed from metals

effective nuclear charge (Z_eff)

• amount of positive charge experienced by an electron in the outermost orbital (how tightly an e^- is held by nucleus)

• increases from L to R across a period and increases going down a group

• Z_eff = Z - S

  • Z = # protons

  • S = # non-valence (shielding) e^-

effective nuclear charge increases from __ to __ across a period and increases going ___ a group

L to R, down

Z_eff = Z - S

number of protons - number of shielding (non-valence electrons)

shielding electrons

non-valence electrons = atomic number of preceding noble gas

ex: Al - Ne is the preceding noble gas and has atomic number 10 → Al has 10 shielding electrons

ionization energy (IE)

• energy needed to remove an electron from an atom

• increases from L to R across a period and increases going up a group

  • includes Noble gases

• exceptions

  • half-filled orbital and filled obitals have greater IE

  • group 2 > group 13 (ex: Mg > B)

    • alkaline earth metals have filled orbitals

  • group 15 > group 16 (ex: N > O)

    • group 15 have half-filled orbitals

ionization energy increases from __ to __ across a period and increases going ____ a group - includes ______ gases

L to R, up, Noble

multiple ionization energy

• 1st ionization energy: energy required to move the outermost e^-

• 2nd, 3rd, 4th: energy required to remove 2nd, 3rd, 4th e^-, etc.

  • if the subsequent e^- is not in the valence shell, it’s more difficult to remove → the value is always LARGER

  • ex: Lithium’s second IE is higher than the first IE

electron affinity (EA)

• amount of energy released when e^- is added to an atom

• increases from L to R across a period and increases going up a group

• exceptions

  • half-filled / filled orgitals have lower EA

    • group 2 < group 1 (ex: Ca < K)

      • group 2 has filled s-orbitals

    • group 15 < group 14 (ex: P < Si)

      • group 15 has half-filled p-orbitals

  • Noble gases have very low EA

    • fillled electron shells

electron affinity increases from __ to __ across a period and increases going _____ a group

L to R, up

electronegativity (EN)

• abiltiy to attract e^-

• increases from L to R across a period and increases going up a group

  • Most electronegative is Fluorine

• exception

  • noble gases have very low EN bc full valence shells

electronegativity increases from __ to __ across a period and increases going ___ a group

L to R, up

summary of periodic trends