Search our library of Chemistry GCSE questions

Top answers

Chemistry

GCSE

what are isotopes and why do they have the same properties?

Isotopes are atoms of the same element that have the same proton number but different nucleon number. TRAIN OF THOUGHT --- Isotopes have the s...

Answered by Sito E. • Chemistry tutor

1782 Views

The mass of a balloon is 0.02g before it is filled with air. After it is blown up with air the mass is 0.04g. Assuming oxygen makes up 21% of air, calculate the number of moles of oxygen in the balloon.

After the balloon has been blown up with air it increased its size by 0.02 g (Final mass - initial mass = mass of the air).We are told that of oxygen takes up 21% of air. Therefore, we need to work out 21...

Answered by Greta S. • Chemistry tutor

2319 Views

Describe the bonding in sodium chloride

Sodium chloride is an ionic compound formed by the strong ionic attractions between positively charged sodium ions (which have lost one electron) and negatively charged chloride ions (which have gained an...

Answered by Matthew F. • Chemistry tutor

3212 Views

In terms of electron transfer describe what happens when one atom of calcium reacts with two atoms of chlorine and give the ions that are formed.

When these atoms react together Calcium chloride, CaCl₂, is formed. Calcium atoms have two electrons in their outer shell, which can be determined from the fact they are in group 2 of the perio...

Answered by Lauren M. • Chemistry tutor

10832 Views

How do endothermic and exothermic reactions differ?

Endothermic reactions take in heat from the surroundings, whereas exothermic reactions release heat to the surroundings. Exothermic reactions release heat as the energy released from the bonds being made ...

Answered by Miss Louise M. • Chemistry tutor

2942 Views