Module 2.2 Electrons, Bonding and Structure Flashcards Preview

OCR AS/A Level Chemistry A > Module 2.2 Electrons, Bonding and Structure > Flashcards

Flashcards in Module 2.2 Electrons, Bonding and Structure Deck (50)
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1

The principle quantum number, n, indicates

The shell that the electrons occupy

2

The larger the value of n,

The further the shell is from the nucleus and the higher the energy level

3

Number of electrons in the first shell

2

4

Number of electrons in the second shell

8

5

Number of electrons in the third shell

18

6

Number of electrons in the fourth shell

32

7

An orbital can

Hold a max. of 2 electrons with opposite spins

An orbital is a region of space where electrons are most likely to be found

8

4 different types of orbital

s
p
d
f

9

S orbitals

Spherical shape

Can hold 2 electrons

10

P orbitals

3D dumbbell shape

Can hold 6 electrons

11

Electron energy levels

1s

2s
2p

3s
3p
4s
3d

4p
4d
4f

12

Filling shells and sub-shells rules

The lowest energy level is filled first

Each energy level must be full before the next higher energy level starts to fill

Each orbital is filled singly before pairing starts

The 4s orbital is at a slightly lower energy level than the 3d orbital. Therefore, 4s fills before 3d

13

Electron configuration of ions

Electrons in the highest energy levels are lost first

14

Ionic bonding

Metal + non-metal

Electrons are transferred from the metal atom to the non-metal atom

Oppositely charged ions formed that attract each other

15

Covalent bonding

Two non-metals

Electrons are shared between the atoms and are attracted to the nuclei of both bonded atoms

16

Metallic bonding

Occurs in metals

Electrons are shared between all atoms

17

Ionic bonds

Electrons are transferred from the metal atom to the non-metal atom

Oppositely charged ions form, which are bonded together by electrostatic attraction

The metal ion is positive (cation)

The non-metal ion is negative (anion)

18

Giant ionic lattices

Each ion is surrounded by oppositely charged ions

These ions attract each other from all directions, forming a 3D giant ionic lattice

*All ionic compounds exist as giant ionic lattices in the solid state but when aqueous, the ions are free to move so they can conduct when aqueous or molten*

19

Ionic compound properties: high melting and boiling points

Ionic compounds are solids at room temperature- a large amount of energy is needed to break the strong electrostatic bonds that hold the oppositely charged ions together in the lattice. Therefore, ionic compounds have high melting and boiling points.

*The greater the charge, the stronger the electrostatic forces between the ions so more energy is required to break up the ionic lattice during melting*

20

Ionic compounds: Electrical conductivity

In a solid ionic lattice:
The ions can't move - can't conduct

When aqueous or molten:
The solid lattice breaks down - the ions are free to move
Can conduct


21

Why do ionic lattices dissolve in polar substances?

The slight charges within the polar substances are able to attract the charged ions in the giant ionic lattice. This means that the lattice is disrupted and the ions are pulled out of it.

22

Covalent bonds

The negatively charged shared pair of electrons is attracted to the positive charges of both nuclei

This attraction overcomes the repulsion between the two positively charged nuclei

Electrons are shared

23

Carbon will always make

4 covalent bonds

24

Nitrogen will always make

3 covalent bonds

25

Oxygen will always make

2 covalent bonds

26

Hydrogen will always make

1 covalent bond

27

In a dative covalent bond,

one atom provides both bonding electrons from a lone pair of electrons

28

For elements in groups 15-17 something weird happens from period 3. What is it?

After covalent bonding, one of the bonding atoms may finish up with more than eight outer shell electrons - "expansion of the octet"

29

Simple covalent structures

The atoms within each molecule are held together by strong covalent bonds

The different molecules are held together by weak intermolecular forces (London forces)

30

Simple covalent properties: Melting and boiling points

Low melting and boiling points:
Weak intermolecular forces
A relatively small amount of energy is needed to break them