Unit 3 - Periodicity

oxidation

when an atom loses electrons (metals)

reduction

when an atom gains electrons (non-metals)

electron affinity

the electron attracting ability of an atom

electronegativity

attraction of an atom to electrons in a covalent bond (how badly an atom wants electrons)

first ionization energy

the amount of energy it takes to remove one mole of electrons from one mole of gaseous atoms

ionization energy equation

X(g) --> X+ (g) + e-

electron affinity equation

X(g) + 1e- = X- (g)

melting points for halogens increases...

going down

electronegativity increases...

up the table, and left to right

electron affinity increases...

up the table, and left to right

atomic radius increases...

right to left, top to bottom

ionic radius increases...

right to left, top to bottom

melting point increases...

up the table and from left to right (w/ electronegativity and electron affinity)

why does melting point for halogens increase going down the PT?

Intermolecular attractive forces

diatomic molecules

HONCl BrIF

alkali metals react with water

2Na (s) + H2O --> 2NaOH + h2

alkali metals reaction w/ halogens

2Na (s) + Cl2 (g) -->2NaCl (s)

alkali metals reaction with oxygen

2Na (s) + O2 (g) --> 2Na2O

most electronegative element

fluorine

alkali metals react violently with which substances?

water, halogens

metal oxides + water produce a(n)...

basic solution Na2O + H2O = 2NaOH

metalloid oxides + water produce a(n)...

amphoteric solution

non-metal oxides + water produce a(n)...

acidic solution SO3 + H2O --> HSO4

metals...

good conductors of heat and electricity, ductile, malleable, have lustre, lose electrons in chemical reactions

nonmetals...

poor conductors of heat and electricity, gain electrons in chemical reactions

metalloids...

have both metallic and non-metallic properties, are sometimes semi-conductors

what elements are metalloids?

boron, silicon, germanium, arsenic, antimony, tellurium, astatine

electronegativity units

don't exist

electron affinity units

kj mol-1

bonding atomic radius

the distance between the two nuclei of the X atoms

non-bonding atomic radius

aka van der waal's radius, when two gaseous aoms collide with one another

bonding radius vs non-bonding radius

bonding radius is always smaller than non-bonding radius

effective nuclear charge

net charge experienced by an electron (Zeff) minus the charge (S) that is shielded or screened by the core electrons Zeff =Z-S

Ex. K --> Z = 19 , there are 18 core electrons and the valence electron doesn't feel the full force of attraction so the effective nuclear charge is 1. 19-18 = 1

electron affinity is positive only for...

noble gases

the more negative the electron affinity value...

the greater the attraction of the ion for the electron

amphoteric

a chemical species that behaves as both an acid and a base

amphiphrotic

particular type of amphoteric species that are either proton (H+) donors or acceptors i.e. H2O, amino acids, proteins