Relative Atomic Mass & Relative Molecular Mass

Question 1

This unified atomic mass is defined as one-twelfth of the mass of a carbon-12 isotope
The symbol for the unified atomic mass is u (often Da, Dalton, is used as well)
1 u =

Answer 1

1 u = 1.66 x 10-27 kg

Question 2

The relative atomic mass (Ar) of an element is the

Answer 2

ratio of the average mass of the atoms of an element to the unified atomic mass unit

Question 3

The relative atomic mass is determined by using

Answer 3

the average mass of the isotopes of a particular element

The Ar has no units as it is a ratio and the units cancel each other out

relative atomic= average mass of 1 atom of x/ 1/12 mass of carbon 12 atom

Question 4

The relative isotopic mass is the

Answer 4

Isotopic abundances refer to the relative proportions of the stable isotopes of each element.

Question 5

isotopes are

Answer 5

Atoms of the same element with a different number of neutrons are called isotopes

Question 6

How to calculate weighted average of the masses of the isotopes

Answer 6

relative atomic mass = isotopic abundance x mass number / 100

Question 7

The relative molecular mass (Mr) is the

Answer 7

The relative molecular mass (Mr) is the ratio of weighted average mass of a molecule of a molecular compound to the unified atomic mass unit

Question 8

The Mr can be found by ………………………….

When calculating the Mr the simplest formula for the compound is used, also known as the formula unit

Answer 8

adding up the relative atomic masses of all atoms present in one molecule

Question 9

The relative formula mass (Mr) is used for

and how is calculated

Answer 9

is used for compounds containing ions

It has the same units and is calculated in the same way as the relative molecular mass