Using the Symbols

Using the Symbols

How to use the symbols

• Each element has a unique symbol, usually one or two letters

• The first letter of an element's symbol is always capitalized, and if there is a second letter, it is lowercase

• For example, the symbol for hydrogen is 'H', and the symbol for helium is 'He'

Na that doesn't make sense

Sometimes, an element's symbol doesn't match its English name because it's based on its name in another language, like 'Na' for sodium, which comes from the Latin word 'natrium'

What about the little numbers?

When we see small numbers written below and to the right of an element's symbol, called subscripts, they show how many atoms of that element are in a molecule, like the '2' in H₂O meaning there are two hydrogen atoms.

The small numbers beside an element's symbol, show how many atoms of that element are in a molecule, like the '2' in H₂O for two hydrogen atoms.

Why NaCl and not ClNa?

Elements are written in a specific order, usually starting with the element that is most to the left on the periodic table, or if the compound contains carbon, it is usually written first, followed by hydrogen.

In a chemical formula, elements are written in a set order, usually starting with the leftmost element on the periodic table, with carbon and hydrogen often listed first.

Multiple Choice

What does the symbol 'Na' stand for?

• Nitrogen

• Neon

• Sodium

• Nickel

Multiple Choice

Why is the symbol for sodium 'Na' and not 'S'?

• 'Na' is easier to remember

• 'S' is already used for another element

• 'Na' comes from the Latin word for sodium

• The scientists decided to make it different

Multiple Choice

What does the small '2' in H₂O indicate?

• The element is diatomic

• There are two molecules of water

• There are two hydrogen atoms in the molecule

• It is the second most common element in water

Multiple Choice

Which element is usually written first in a chemical formula if it’s present?

• Oxygen

• Carbon

• Hydrogen

• Nitrogen

Multiple Select

If a compound has the formula CO₂, what does this tell you?

• There are two carbon atoms

• There are two oxygen atoms

• The compound contains two elements

• The oxygen is written first

Please go to the all year 8 stile page and complete the task called "week 5 - elements and compounds"