Lesson Notes By Weeks and Term v5 - Grade 8

Lesson Video

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Performance objectives

• Define atom, element, proton, neutron, and electron.
• Describe the structure of an atom.
• Calculate the number of protons, neutrons, and electrons.
• Explain the organization of the periodic table.
• Relate an element's position to its properties.

Lesson summary

This week, we delve into the fascinating world of atoms – the tiny building blocks that make up everything around us, from the air we breathe to the soil beneath our feet, to the food we eat! Understanding atomic structure is crucial because it allows us to predict how different substances will behave and interact. This knowledge is vital for many aspects of South African life, including understanding the impact of mining on the environment, developing new medicines from indigenous plants, and creating sustainable solutions for energy and water. We will also explore the periodic table, a powerful tool that organizes all known elements based on their atomic structure and properties.

Lesson notes

What is an Atom? An atom is the smallest particle of an element that can exist and retain the chemical properties of that element.

Think of it like this: if you keep breaking down a piece of gold (Au), eventually you'll get to a point where you can't break it down further without it no longer being gold. That smallest piece is an atom of gold.

Subatomic Particles: Atoms are made up of even smaller particles called subatomic particles: Protons: Positively charged particles located in the nucleus (the center) of the atom. The number of protons determines what element an atom is. For example, all atoms with 6 protons are carbon atoms.

Neutrons: Neutrally charged (no charge) particles also located in the nucleus. Neutrons contribute to the mass of the atom but do not affect the element's identity.

Electrons: Negatively charged particles that orbit the nucleus in specific energy levels or shells. They are much lighter than protons and neutrons.

Atomic Number and Mass Number: Atomic Number (Z): The number of protons in the nucleus of an atom. The atomic number identifies the element. The atomic number is usually found above the element symbol in the periodic table.

Mass Number (A): The total number of protons and neutrons in the nucleus of an atom. Mass number = Number of protons + Number of neutrons.

Calculating the Number of Neutrons: Number of neutrons = Mass number (A) – Atomic number (Z)