AP Chemistry Unit 2

unit 2 terms and things to remember

what is true for electronegativity bonds?

as size (radius) of an atom decreases the electronegativity increases - smaller equals mightier

what are metallic bonds?

2 metals, large, valence electrons donated to electron sea

• closer to francium = more metallic

• closer to helium = more non-metal

• metalloids = boundary between metals and non metals 

what are covalent bonds?

2 non-metals, valence electrons overlap and electrons are shared by the atoms

• unpaired electrons are shared between atoms

• polar - both atoms in the bond have electronegativity difference greater than 0.4

• non-polar - both atoms in the bond have similar electrons (same element of carbon bonded to hydrogen)

what are ionic bonds?

dissimilar electronegativity therefore valence electrons stay with in the more electronegative atom (non-metal)

• bond is usually between a metal and a non-metal

• can come apart to positive and negative ions

• big difference in the electronegativity between atoms

what is bonding energy?

as two atoms approach they have the potential to form a bond, where orbitals overlap the more stable the bond the higher the bond energy

aka - how hard it is to break bonds between atoms

what is bond order? 

COVALENT ONLY - the number of bonds between atoms, the more bonds the shorter and stronger the bond is

what is the difference between anions and cations?

anions - tend to be non-metals

cations - tend to be metals

what is the difference between soluble and nonsoluble salts?

soluble - dissolves completely in water

non-soluble - doesn’t dissolve completely in water

what is the pattern of alternating charges?

alternating ions between positive and negative charge - maximizes coulombic attraction and minimizes repulsion

what is lattice energy?

the strength of ionic bond in a compound and completely controlled by coulombic force

(comes apart easy = low lattice energy)

what is an interstitial alloy?

different size elements filling in the gaps between atoms, not flexible

what is a substitutional alloy?

different metals with similar sized radii, flexible