Atomic Structure pt 2

Question 1

Why have mass spectrometers been included in planetary space probes

Answer 1

So that elements on other planets can be identified as elements on other planets can have a diff composition of isotopes

Question 2

What is the parent ion or the Molecular ion

Answer 2

The isotope with the highest m/z will be equakl to the relative molcular mass

Question 3

Define first ionisation energy

Answer 3

The enthalpy change when one mole of gaseous atoms forms one mole of gaseous ions with a single positve charge

Question 4

Define secon ionisation energy

Answer 4

The enthalypy chnage when one mole of a gaseous ions with a single positiove charge forms one mole of gaseous ions with a double positive charge

Question 5

What are the factors that affect ionisation energy(3)

Answer 5

• The attraction of the nucleus-The more protons in the nucleus the greater the attraction
• The distance of the electrons from the nucleus-The further the distance the weaker the attraction to the nucleus
• Shielding of the attraction of the nucleus-An electron in the outershell is repelled by electrons in complete inner shells weakening the attarction of the nucelus

Question 6

Why are successive ionsation energies always larger

Answer 6

• When the first electron is removed a postive ion is formed
• The ion increases the attraction on the remaining electrons and so enegry required to remove the next electron is larger

Question 7

What so the formula for the amount of electrons allowed to be held by each electron shell l

Answer 7

2n^2
n= number of shells

Question 8

What is a mass spectrometer used for

Answer 8

The accurate determination of Relative atomic mass (Ar)

Question 9

Why does the ionisation energy increase across a period

Answer 9

Because the nuclear charge is increasing and this makes it harder to remove an electron

Question 10

Why does ionisation energies decrease as you go down a group

Answer 10

the outermost electron is, on average, farther from the nucleus, meaning it is held less tightly and requires less energy to remove.

Question 11

Why is there a small drop in ionisation energies from Mg to Al?

Answer 11

• Al is starting to fill a 3p subshell whereas Mg has its outer electrons in the 3s sub shell
• The electrons in 3p subshell are slightly easier to remove beacuse the 3p electrons are higher in energy and are slightly shielded by the 3s electrons

Question 12

Why is there a small drop from Phosphorus (P) to Sulfur (S)

Answer 12

• With sulfur there are 4 electrons in the 3p subshell and the 4th is starting to fully fill the first 3p orbital
• When the second electron is added to a 3p orbital there is a slight repulsion between the two negatively charged electrons which makes the second electron easier to remove

Question 13

What element has the highest second ionisation energy

Answer 13

Litihium as it will form a positive ion and have no inner shells as it only has the 1s sub shell left over