unit 1 section 3 miss jessup

Question 1

Why are metals good conductors of electricity

Answer 1

They contain delocalised electrons which cause a negative charge to flow

Question 2

Malleable

Ductile

Answer 2

Layers of ions can slide past each other when a force is applied

Bonding and structure maintained after distortion

Question 3

High melting points because

Answer 3

Metallic bonds have strong esfoa between positive ions and delocalised electrons , lots of energy is needed to overcome metallic bonds

Question 4

4 factors affecting bond strength

Answer 4

Size of ion - smaller ions have higher charge density
Charge on ion - higher charge means higher esfa between positive and neg ions
No of delocalised electrons more = stronger bonding
Lattice structure - different arrangements of ions can affecting melting points

Question 5

What is a ionic bond

Answer 5

Force of attraction between a positively charged metal ion and negatively charged non metal ion

Question 6

Ionic compounds can conduct electricity when
What is the mp of giant ionic lattices
Why are ionic compounds soluble

Answer 6

Molten or dissolved because the ions are free to move
High because they are held together by strong electrostatic forces which take lots of energy to overcome
The polar water molecules pull the ions away from the lattice causing it to dissolve

Question 7

What’s a co ordinate (dative bond ) bond

Answer 7

A shared pair of electrons in which both electrons come from the same atom

Question 8

Define a lone pair of electrons

Answer 8

A pair of electrons in the outer shell of an atom that isn’t involved in bonding with other atoms

Question 9

What’s a triple covelant bond
Double covelant bind?

Answer 9

Where two atoms share three pairs of electrons .
When an atom sharks 2 pairs of electrons

Question 10

What is the valence shell electron pair, repulsion theory?

Answer 10

Lone pairs of elec have greater repulsion than bond pairs , reduce bond angles when present bc bonding pairs r push together by lone pair repulsion

Question 11

define electronegativity ?

Answer 11

the ability of an atom to attract a pair of electrons in a covalent bond

Question 12

in a polar bond the difference in electronegativity causes a
a dipole…

Answer 12

dipole
Is a difference in charge between 2 atoms caused by a shift in electron density in the bond

Question 13

Electro negativity depends on 2 factors

Answer 13

Size of positive charge on nucleus - as u move from left to right , no. Protons increase , which increases the attraction between nucleus and and pair of electrons in the covelant bond

Shields - The greater the number of inner shells the lower electronegativity

Question 14

Define a polar covelant bond
Non polar bond
Define permanent dipole

Answer 14

A bond formed when a shared paired of electrons are not shared equally
They form between atoms of elements with the same electronegativity
When charge is distributed unevenly throughout the whole molecule

Question 15

Intermolecular forces …

Answer 15

Exist between molecules, including van der walls , permanent dipole dipole , and hydrogen bonds

Question 16

Van der walls forces ..l

Answer 16

1. Caused by random electron movements
2. At times elect in atoms can be more on one side than the other
3. Forming temp dipole
4. This td can cause another td in the opposite direction in a neighbouring atom.
5. 2 dipoles then attracted to each other

Question 17

What can affect the strength of van de walls forces

Answer 17

-Larger molecules have larger electron clouds , meaning stronger forces
- shape : long straight molecules lie closer together than branched ones , the closer the 2 molecules the stronger the forces

Question 18

Dipole dipole forces …

Answer 18

Molecules containing permanent dipoles there will be weak electrostatic forces of attraction between the positive and neg deltas on neighbouring molecules

Question 19

Hydrogen bonding

Answer 19

• strongest intermolecular force
• only happens when h2 is bonded to fluorine, nitrogen , oxygen as these are very electronegative they draw bonding electrons away from, hydrogen atom .
• the lone pair on these atoms form weak bond with a hydrogen atom from another molecule

Question 20

Properties of period 3 elements - atomic radius

Answer 20

As u go along period atomic radius decreases as nuclear charge increases bc electrons are pulled closer to + nucleus .

Question 21

Protperties of period 3 elements - melting points

Answer 21

Na , mg , al = increases as metallic bonds get stronger due to increasing nucleur charge , meaning more delocalised electrons and a decreasing atomic radius

Silicon - giant covelant structure , lots of energy to break covelant bonds

Phosphorus to argon - molecular substances , mp depend on strength of vanderwalls forces , more atoms in the molecule = stronger vanderwalls = higher mp

Question 22

Properties of period 3 elements - first ionisation energy

Answer 22

Increases bc of the increasing attraction between the outer shell electrons and nucleus , due to the number of protons Increasing