Chemistry Year 8

Atoms!

​Building blocks of all matter

Atoms make up all matter
Their arrangement determines the state of the substance
Their arrangement also determines the physical and chemical properties of the substance

Atoms have a nucleus made up of protons and neutrons
Protons are positively charged particles.
Neutrons have no charge.
The Mass number is the sum of protons and neutrons

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Electrons orbit the nucleus
They are negatively charged particles.
For atoms, the number of protons equals the number of electrons, which equals the atomic number

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The atomic number is the top number. It tells you how many protons and electrons the element has.
Atomic No. = Protons = Electrons
The bottom number is the mass number.
It tells you what the number of protons and neutrons add up to

​Mass No. = protons + neutrons
Sodium: 11 protons, 11 electrons
How many neutrons does sodium have?

Multiple Choice

Lithium has an atomic number of 3. Therefore it has 3 protons

• True

• False

Match

Match the element with the number of electrons it will have? (Hint: you are matching the atomic number with the element)

• He

• S

• O

• Be

• Na

2

16

8

4

11

• 2

• 16

• 8

• 4

• 11

Categorize

Options (16)

silver

gold

copper

aluminium

iron

platinum

zinc

lead

oxygen

nitrogen

sulfur

phosphorus

chlorine

carbon

helium

neon

Place the elements in the right category

metal

non metal

Postman Pat Electrons

Electrons occupy specific shells or orbitals
Each orbital can manage only a certain number of electrons (we explain why in Stage 6 Chemistry)
The first shell can only handle a maximum of 2
The second shell, a maximum of 8
The third shell, a maximum of 8
That's where we stop in Year 8!

Li: ATOMIC NUMBER 3, therefore 3 electrons:

C: ATOMIC NUMBER 6, therefore 6 electrons:

Cl: ATOMIC NUMBER 17, therefore 17 electrons:

Ne: ATOMIC NUMBER 10, therefore 10 electrons:

Multiple Choice

Which element would have an electronic configuration 2, 8, 1?

• Sodium (Na)
• Potassium (K)
• Aluminum (Al)
• Magnesium (Mg)

Multiple Choice

How many electrons does aluminium have in its OUTER most shell?

• 1
• 5
• 3
• 8

Multiple Choice

Which elements have the same number of electrons in their outer most shell?

• Na and Li

• C and N

• Ne and F

• O and Na

Poll

Today I learned

• how to work out the number of electrons in an element

• the electron arrangement for different elements

• the number of electrons each shell can take

• to work out how many neutrons an element has