Atomic Structure

Question 1

What is Atomic number

Answer 1

The atomic number of an atom is the number of protons in its nucleus.

Question 2

What is Mass number

Answer 2

The mass number of an atom is the number protons plus neutrons in its nucleus.

Question 3

What are isotopes

Answer 3

Isotopes are atoms of the same element which have the same number number of protons but different number of neutrons

Question 4

Symbol, charge and mass of an electron

Answer 4

e-, 1- and 1/1840

Question 5

Symbol, charge and mass of an Nuetron

Answer 5

n, 0 and 1

Question 6

Symbol, charge and mass of an proton

Answer 6

p, 1+ and 1

Question 7

What is relative isotopic mass

Answer 7

Relative atomic mass is the mass of one atom of an isotope relative to 1/12th of the mass of an atom of the isotope carbon-12

Question 8

What is relative atomic mass

Answer 8

Relative atomic mass is the average mass of an atom of an element relative to 1/12th of the mass of an atom of the isotope carbon-12

Question 9

Calculation of relative atomic mass

Answer 9

Relative atomic mass = average mass of an atom of the element/ 1/12th x the mass of one atom of carbon-12
eg. magnesium-24 : 78.6%
magnesium-25 : 10.1%
magnesium-26 : 11.3%
1. total relative mass of 100 atoms of magnesium-
(78.6x24) + (10.1x25) + (11.3x26) = 2432.7
2. the average relative atomic mass= 2432.7/100=24.3(3sf)

Question 10

What is relative molecular mass

Answer 10

Relative molecular mass of an element is the sum of all the relative atomic masses of all the atoms in the molecular formula

Question 11

What is relative formula mass

Answer 11

Relative formula of a compound is the sum of all the relative atomic masses of all the atoms in its formula