C1 - Elements

Question 1

What is an element?

Answer 1

-A substance made up of atoms that all have the same number of protons in their nucleus.

Question 2

What do protons decide?

Answer 2

-What type of atom it is.

Question 3

If a substance only contains atoms with the same number of protons, what is it called?

Answer 3

-An element.

Question 4

What are atoms represented by?

Answer 4

-By letter symbols.

Question 5

What are isotopes?

Answer 5

-Isotopes are different forms of the same element. They have the same number of patrons but a different number of neutrons.

OR

-They have the same atomic number but different mass numbers.

Question 6

As many elements can exist as a number of different isotopes, what is used to refer to the element as a whole instead of the mass number?

Answer 6

-The relative atomic mass (Ar).

Question 7

What is the formula used to work out the relative atomic mass (Ar) of an element?

Use it to solve this:

Copper has two stable isotopes. Cu-63 has an abundance of 69.2% and Cu-65 has an abundance of 30.8%. Calculate the relative atomic mass of copper to 1 decimal place.

Answer 7

Ar = sum (of isotope abundance x isotope mass number) DIVIDED BY sum of abundances of all the isotopes

Ar = (69.2 x 63) + (30.8 x 65) DIVIDED BY 69.2 + 30.8

= 4359.6 + 2002 DIVIDED BY 100

= 6361.6 DIVIDED BY 100

=63.6