Year 10 Science · Unit 2 · Lesson 21

Inside the Atom's Nucleus, Nuclear Stability

Foundation Worksheet

Name

Date

Class

Learning Goals

Recall the particles in the nucleus and the meaning of atomic number and mass number.
Sort terms into the correct group: parts of the nucleus, ideas about isotopes, and ideas about stability.
Read simple nuclide symbols and state the conditions that make a nucleus unstable.

Warm Up

Fill the gap

Choose the correct word from the word bank to complete each sentence. Two words will NOT be used.

protons neutrons nucleons isotopes strong nuclear force electrostatic radioactive electrons mass number

The two particles found in the nucleus are and neutrons. Together these nuclear particles are called . The number of protons is the atomic number, and it decides which element the atom is. Atoms of the same element that have different numbers of neutrons are called . Protons all carry a positive charge, so they push each other apart with an repulsion. The nucleus is held together by the , which acts over a very short range. When a nucleus has the wrong balance of particles it becomes unstable, or , and breaks down over time. The total number of protons plus neutrons is called the of the atom.

Your Turn

Sort it!

Write each term from the pool into the correct box below. Each term belongs to exactly one box.

Proton (+1 charge) Neutron (no charge) Atomic number (Z) Mass number (A) Carbon-12 and carbon-14 Same protons, different neutrons Protium, deuterium, tritium Chemically identical atoms Strong nuclear force Neutron-to-proton ratio Band of stability All elements above bismuth (Z > 83)

Parts of the Nucleus

Isotopes

Nuclear Stability

Show What You Know

1. For the nuclide ²³₁₁Na (sodium-23), state the number of protons, the number of neutrons, and the number of electrons in a neutral atom.

Recall 2 marks

2. Name the two conditions that can make a nucleus unstable, and name the force that normally holds a nucleus together.

Recall 2 marks

Wrap Up

In one sentence, explain why carbon-12 and carbon-14 are both still carbon even though their nuclei are different.