Year 8 Science · Unit 2 · Lesson 06
Foundation Worksheet
Learning Goals
Fill the gap
Choose the correct word from the word bank. Two words will not be used.
The small, dense centre of an atom is the . It holds , which each carry a charge, and , which carry no charge. Much lighter particles called are found outside the centre, and each carries a charge.
1. The nucleus is tiny, yet it holds almost all of the atom’s mass. Name the two particles that give it that mass, and state which particle is much lighter.
True or false? Fix the false ones
Circle T or F. If a statement is false, correct it on the line.
1. The nucleus holds most of the atom’s mass, even though it is very small.
Correct it:
2. An atom with 6 protons and 6 electrons has no overall charge.
Correct it:
3. Protons are found outside the nucleus, moving in the space around it.
Correct it:
4. A neutron is the same thing as a neutral atom, because both have no overall charge.
Correct it:
5. An ordinary hydrogen atom is neutral even though it has no neutrons.
Correct it:
2. Helium has two of every kind of subatomic particle. Draw a simple model of a helium atom. Label the nucleus, a proton, a neutron and an electron, and mark each particle with its charge (+, 0 or −).
3. Your drawing is not to scale. Which part of it is drawn far too big compared with the whole atom, and what does the real atom have that a drawing cannot show?
Scenario: pom-pom atoms
Each group in a class was asked to model one neutral atom using craft supplies: large green pom-poms for protons, large yellow pom-poms for neutrons and tiny blue sequins for electrons. Group 4 also glued all of its sequins into the centre with the pom-poms.
| Group | Atom asked for | Green (protons) | Yellow (neutrons) | Blue sequins (electrons) | Overall charge of the model |
|---|---|---|---|---|---|
| 1 | Hydrogen | 1 | 0 | 1 | |
| 2 | Helium | 2 | 2 | 2 | |
| 3 | Lithium | 3 | 4 | 2 | |
| 4 | Carbon | 6 | 6 | 6 |
Source: sample class results.
4. Complete the last column of Table 1. Which group did not build a neutral atom? State what they must add to fix it.
5. Group 4 has the right numbers but still built a wrong model. Explain their mistake. Then use Groups 1 and 2 to explain why adding neutrons never changes the overall charge.
6. A student says: “A neutron is just a neutral atom, and because it has no charge it does not matter.” Explain the two mistakes in this statement. Use the charge, location and mass of the neutron in your answer.
Fill the gap
nucleus; protons; positive; neutrons; electrons; negative. Not used (2): molecule, shell.
1. Protons and neutrons (similar mass). The electron is much lighter. [2 marks]
True or false
1. True. 2. True. 3. False: protons are in the nucleus; electrons are the particles outside it. 4. False: a neutron is one particle in the nucleus; a neutral atom is a whole atom with as many electrons as protons. 5. True.
2. Nucleus in the centre containing 2 protons (+) and 2 neutrons (0); 2 electrons (−) outside the nucleus. [3 marks: 1 correct numbers, 1 electrons outside the nucleus, 1 labels and charges]
3. The nucleus is drawn far too big (a real atom is about 100 000 times wider than its nucleus). The real atom is almost entirely empty space. [2 marks]
Go Deeper
4. Overall charge: Group 1: 0; Group 2: 0; Group 3: +1; Group 4: 0. Group 3 has 3 protons but only 2 electrons, so they must add 1 more blue sequin (electron). [3 marks: 1 column, 1 Group 3, 1 add one electron]
5. Electrons are found outside the nucleus, not in it; only protons and neutrons belong in the centre. Groups 1 and 2 are both neutral although one has 0 neutrons and the other 2, because neutrons have no charge; only protons (+) and electrons (−) set the overall charge. [3 marks: 1 electrons outside, 1 neutrons carry no charge, 1 evidence from Groups 1 and 2]
Show What You Know
6. Marking guide: 1 a neutron is a single particle in the nucleus with no charge, while a neutral atom is a whole atom; 1 an atom is neutral because it has equal numbers of protons (+) and electrons (−), whatever its neutrons; 1 neutrons add mass to the nucleus (similar mass to a proton); 1 neutrons help hold the nucleus together, so protons do not push it apart. [4 marks]
Common error to watch for: thinking neutrons affect the overall charge, or placing electrons in the nucleus. Name the particle by its charge first, then place it.