AQA GCSE Chemistry: Paper 1: Unit 1 - Atomic structure and the periodic table

These are flashcards on the subject: AQA GCSE Chemistry: Paper 1: Unit 1 - Atomic structure and the periodic table. I shall be adding more flashcards as I get further along the course.

How many different elements are there

There are around 100 different element, which are shown in the periodic table.

What do the symbols in the periodic table represent?

Each symbols in the Periodic Table represents a different element.

What is an element?

In an element, all of the atoms are the same. Every element has a symbol, and every symbol starts with a capital letter. (for example, the symbol for Magnesium is Mg, whilst the symbol for sulfur is simply S.)

What is a compound?

A compound contains two or more different elements, chemically combined in fixed proportions, which usually have totally different properties to the elements that they’re made from.

What does fixed proportions mean.

The elements in a compound are always combined in the same ratio. For example, water is H₂O, which has 2 hydrogen atoms and 1 oxygen atom, which means water always have a ratio of 2:1. You cant change the ratio and still have water.

What do you need to use in order to separate a compound back into its elements?

A chemical reaction, which isn’t always easy to do.

What is a mixture?

Different elements or compounds, but they’re not chemically combined

How do you separate a mixture?

You use a physical separation technique, rather then a chemical reaction.

What are 4 examples of a physical separation technique?

• Filtration

• Distillation

• Crystallisation

• Chromatography

What is a molecule?

A molecule consists of two or more atoms chemically bonded together. The atoms can be from the same element or different elements. Methane (CH₄) is an example of a molecule, which is a compound, whereas Chlorine (Cl₂) is an example of a molecule, which is an element.