Bonding and thermochemistry

Question 1

Structure and bonding of ionic solids

Answer 1

Ionic solids are 3D lattices composed of ions held together by iconic bonds. These bonds are string and directional

Question 2

Structure and bonding of metallic solids

Answer 2

Metallic solids are 3D lattices composed of metal atoms held together by metallic bonds. Metallic bonds are strong and non-directional (valance e are attracted to multiple metal nuclei) Metal atoms are ion a sea of electrons, the electrons are delocalised.

Question 3

Structure and bonding of Covalent network solids

Answer 3

Diamond: A 3D lattice of C atoms, each C is covalently bonded to four other C arms in a tetrahedral shape

Graphite: a 2D lattice of C atoms, each C is covalently bonded to 3 other C atoms In layers. Each layer is held to other layers by weak forces.

Silica: A 3D lattice of Is and O atoms covalently bonded to each other in a 1:2 ratio

Question 4

Structure and bonding of molecular solids

Answer 4

Molecular solids are 3D lattices composed of molecules held together by molecular bonding

Question 5

What depends on a 3D shape of a molecule?

Answer 5

1. the number of areas of electron density around the central atom
2. the regions of negative charge REPEL
3. how many of those areas are bonded and non-bonded

Question 6

What does the bond angle depend on

Answer 6

The total number of electron density around the central atom repelling

Question 7

2 total, 2 bonded

Answer 7

Linear shape plus 180 degrees

Question 8

3 total, 3 bonded

Answer 8

Triangular planar plus 120 degrees

Question 9

3 total, 2 bonded

Answer 9

(parent shape triangular planar) V shaped, bent plus 120 degrees

Question 10

4 total, 4 bonded

Answer 10

Tetrahedral shape, plus 109.5 degrees

Question 11

4 total, 3 bonded

Answer 11

(P.S tetrahedral) Trigonal planar, plus 109.5 degrees

Question 12

4 total, 2 bonded

Answer 12

(PS. tetrahedral) V shape/bent, plus 109.5 degrees

Question 13

is what electronegativity

Answer 13

The ability of an atom to attract boning electrons
FONCl (4 most EN elements)
H is relativity low

Question 14

Polar bonds main ideas:

Answer 14

the more EN an element is, the stronger it’s ability is to attract electrons from the other bonded element.
so.. More EN means a partial charge of negative s (with a dandi)
A polar bond forms when 2 elements are different from each other (otherwise that bonds would be non-polar)

Question 15

Molecular polarity main ideas:

Answer 15

To have a polar molecule, there must be polar bonds- different elements (otherwise the molecule will be non-polar too).
Whether the polar bonds are arranged symmetrically- meaning dipoles cancel therefore molecule is non-polar- or asymmetrically- meaning dipoles do not cancel therefore molecule is polar.
(So looking at shape is an idea)
V shaped= AS= dipoles don’t cancel= polar molecule
Linear= SM= dipoles cancel= non-polar molecule
Triangular planar= AS= Dipoles do not cancel= polar
Tetrahedral= SM= dipoles cancel= non polar molecule
BUT if there’s something like CCl2Br2, even with the tetrahedral arrangement of SM, Cl and Br have different EN causing different dipoles, dipoles do not cancel so molecule is polar.