Electron Structure

Question 1

Where are electrons found

Answer 1

3D regions of space called orbitals

Question 2

What is Heisenberg’s uncertainty principle

Answer 2

We can never be exactly sure where an electron is

Question 3

How many electrons fill the first 4 shells?

Answer 3

2,8,18,32

Question 4

Maximum number of electrons in a shell’ n’ is given by the formula …

Answer 4

2n^2

Question 5

Shells - energy

Answer 5

Regarded as energy levels

Energy increases as the shell number increases

Question 6

What’s the principal quantum number

Answer 6

The number representing the overall energy of each orbital or shell( shell number)

So n=2 is the second shell

Question 7

What is an orbital

Answer 7

A region that can hold up to 2 ELECTRONS

OPPOSITE spins

3D region of space in which there is a >95% chance of finding an electron

Question 8

What are sublevels

Answer 8

Have electrons orbitals

Each initial can hold 2 electron

Question 9

S orbitsl

Answer 9

The electron cloud is within the shape of a sphere

Each shell from n=1 contains ONE s orbital

The greater he shell number n, the greater the radius of its s orbital

2 orbitals in sun level

Question 10

P orbital

Answer 10

Electron cloud is within he shape of a dumb bell

3 p orbitals at sub- shell level

Each shell from n=2 contains 3 p orbitals

The greater the shell number ‘n’, the further the p orbtial is from the nucleus

6= MAX no. Of electrons in sublevel

Question 11

What is the order of number of sublevels in orbitals from s-p-d-f

Answer 11

1,3,5,7

TIMES BY 2 FOR 2 ELECTRONS

Question 12

D orbital

Answer 12

Each shell from n=3 contains 5 d orbitals

Max no. Of electrons in shbshell =10

Question 13

F orbital

Answer 13

Each shell from n=4 contains 7 f orbitals

Max number of electrons in shbshell is 14

Question 14

What are subshells/ levels

Answer 14

Within a shell, orbitals of the SAME type( p,f,s etc) are grouped together as subshells

Question 15

In SHELLS

Answer 15

Subshells of s, p, d and f

Question 16

The periodic table- shells

Answer 16

The periodic table is split into BLCOKS

A s block element is one whose outer electron is filling a s - sub shell , highest energy electron is s subshells

Question 17

3 rules for how orbitals are filled?

Answer 17

• electrons pair with opposite spins
• orbitals fill in order of increasing energy
• orbitals with the same energy are occupied singly first

Question 18

Orbitals fill in order of increasing energy

Answer 18

• aufbau principle
• the subshells that make up shells have slightly different energy levels
  Within each shell, the new type of sub shell added has a HIGHER energy

The 3D subshell is at a HIGHER energy than the 4s subshell, so the 4s fills first - 3p,4s,3D

Question 19

Electrons pair with opposite spins

Answer 19

Each orbital can hold up to TWO electrons

Electrons are negatively charged and repel one another

They have a property called SPIN - either up or down

An electron is shown as an arrow, showing its spin. Either UP or down

Opposite spins help counteract with repulsion between negative charged of 2 electrons

Question 20

Orbitals with the same energy are occupied singly first

Answer 20

Within a subshell, the orbitals have the same energy

One electron occupies each orbital before pairing starts , this prevents ANy repulsion between paired electrons until there is no further orbital available at the same energy level

HUNDS RULE

Question 21

Exceptions to normal electron configuration

Answer 21

Cr and Cu

Question 22

Cr

Answer 22

1s^2 
2s^2 
2p^6 
3s^2
3p^6 
4s ^1 
3D ^5

Question 23

Cu

Answer 23

1s^2 
2s^2
2p^6
3s^2
3p^6
4s^1
3d^10

Question 24

Why are Cr and Cu exceptions

Answer 24

the arrangements are slightly lower energy arrangements as the reduced electron electron repulsion makes up for the fact that one electron is in a slightly higher energy level

Question 25

Electron configuration? How do the orbitals go?

Answer 25

1s 
2s 
2p (3) 
3s 
3p 
4s 
3d (5)
4p

Question 26

Group 8 elements - electrons in outer shell

Answer 26

He -2
Ne - 10
Ar-18

E.g. oxygen - {he} 2s^2 2p^4

Question 27

If you have to draw the electron structure for ions, (boxes) how do you do it?

Answer 27

Fill up the orbitals for the ion as their atoms
Take out any 4s electrons first
Then remove further electrons from 3 d

Question 28

Why do you remove 4s electrons before 3D - ions

Answer 28

Once filled, the 3D energy level falls below the 4s energy level, so it empties before 3D subs hell , (because it’s at a Lower energy level than 3D subs hell before - fills first)