Mole Concept

Question 1

Given ¹⁹₉F: what is its atomic number / proton number and what is its atomic mass, and neutron no.?

Answer 1

Mass: 19
Proton: 9
Neutron is 10

Question 2

What happens when the number of subatomic particles are not equal?

Answer 2

The atom is now called an ion

Question 3

Define a cation?

Answer 3

This is when there’s more proton than electron, so the atom becomes positively charged in the difference amount.

E.g 10 proton and 8 electron means the atom had a + 2 charge

Question 4

Define an anion?

Answer 4

An atom that gains one or more electrons will exhibit a negative charge.

Question 5

Define Isotopy

Answer 5

This is a phenomenon whereby atoms of an element have the same atomic number but different mass number, this difference is caused by a difference in the number of neutron.

Question 6

Define isotopes and the why behind them?

Answer 6

Isotopes of an element exhibit different physical properties but the same chemical properties because neutron have no effect on the chemical properties of the atom but on its mass.

Question 7

How is the mass of an atom determined and why?

Answer 7

Due to the size of atoms, it’s impossible to weigh a single one clearly. It is possible to determine the size of mass of one atom but only relative to another one. So a uniform mass scale is necessary to build such a system.

Question 8

Define the atomic mass scale

Answer 8

This is a relative scale which is more suitable for calculating atomic masses and it uses the atomic mass unit to function.

Question 9

Define the atomic mass unit?

Answer 9

This is the unit used for the atomic mass scale. An isotope of carbon. c - 12 was chosen. 1 atom of ¹²C has a mass of 12u or 12amu

So 1amu = 1/12 of C - 12 atom

Question 10

What’s the value of 1 amu in grams

Answer 10

1.6606x10⁻²⁴ g