Atoms, elements and compounds

Chemistry

3 groups spaced apart, each containing 2 touching grey circles

2 groups spaced apart, each containing 3 touching circles, one of which is white, one of which is black and one of which is grey

9 grey circles all touching, arranged in a 3 by 3 square

All diagrams show an element, except one. Which does not show an element?

A substance that has two or more different elements chemically bonded together is a {{}}.

Elements are determined by the number of {{}} in the nucleus.

The name of the compound that contains one potassium atom, one carbon atom and three oxygen atoms is {{}}.

KCO3 (with the 3 as a standard case number)

The formula for the compound that contains one potassium atom, one carbon atom and three oxygen atoms is ...

two or more different elements chemically bonded together

All 118 known elements are displayed in the {{}}.

Calcium is added to hydochloric acid to produce calcium chloride and hydrogen. What are the **two** reactants?

Iron oxide breaks down into iron and oxygen. What are the **two** products?