1. Atomic Structure

2. Starter
True or False…?
Atoms cannot be split up into anything smaller.
Atoms are solid objects and nothing can pass through them.
There are millions of different kinds of atoms.

3. Starter Think, Pair and Share… True or False…?
Atoms cannot be split up into anything smaller.
Atoms are solid objects and nothing can pass through them.
There are millions of different kinds of atoms.
No-one has ever seen an atom.
False!
False!
False!
False!

4. What is an atom made of?
The nucleus is made up of positive protons, and neutral neutrons. The nucleus is surrounded by electrons. These electrons are arranged in layers, or shells, sometimes these shells are called energy levels.
Electron
Nucleus
Electron Shells
Proton
Neutron

5. What is an atom made of?
Complete your table using the information about sub-atomic particles around the room.
Particle
Relative Charge
Relative Mass
Where in the atom is it found?
Proton
+ 1 1
In the nucleus
Neutron
Electron
- 1
Almost 0 (actually )
In shells surrounding the nucleus

6. Atomic number and mass number
So far scientists have identified 118 different types of atom. This means there are 118 different elements. Each element has a fixed number of protons in its nucleus. Look at Lithium (Li) on your Periodic Table.

7. Atomic number and mass number
This is the atomic number for lithium. This number tells us how many protons are in the nucleus. No other element has the same atomic number as lithium.
We know that the ‘Li’ is the chemical symbol for lithium, but what do those numbers mean? Li 7 3
This is the mass number. The mass number of an atom is the total number of protons and neutrons in the nucleus.

8. Atomic number and mass number
You can use the nuclear symbol for an atom to work out the number of protons and neutrons in the nucleus. The nuclear symbol for Phosphorus (P) is shown below. How many protons and neutrons are in its nucleus? P 31 15

9. Atomic number and mass number
The atomic number is 15. This is the number of protons in the nucleus. The mass number is 31. This is the total number of protons and neutrons in the nucleus. So, 31 – 15 = 16. P 31 15

10. Test Yourself
Using the nuclear symbols shown for these atoms, write down the numbers of protons and neutrons in the nucleus of each atom.
An atom of potassium (K), has 19 protons and 20 neutrons in its nucleus. Write down the nuclear symbol for this atom. O 16 8 Na 23 11

11. K Test Yourself Swap your work with the person sitting next to you.
Oxygen (O) has 8 protons and 8 neutrons. Sodium (Na) has 11 protons, and 12 neutrons.
The nuclear symbol for potassium should look like this: K 39 19

12. Worksheet 1 Missing words
Protons Equal
Neutrons Different
Electrons Atomic
Electrons Periodic
Electrons Protons or electrons
Protons Identical Atoms
Negative Protons plus neutrons
Atoms Protons, electrons and neutrons
Nucleus

13. Answers