📖 Part A: Definitions — Model Answers

Accept responses that convey the same meaning. Key terms are highlighted in bold.

✅ A pure substance made of only one type of atom that cannot be broken down into simpler substances by chemical means.

✅ The smallest particle of an element that still has the chemical properties of that element.

✅ The number of protons found in the nucleus of an atom of that element. It identifies the element on the periodic table.

✅ A organised arrangement of all known elements, ordered by increasing atomic number and grouped by similar chemical properties.

🔬 Part B: Classification Activity — Answer Guide

Students classify each element as a metal, non-metal, or metalloid. Correct answers below.

✅ Metals: Shiny lustre, good conductors of heat and electricity, malleable, ductile.

✅ Non-metals: Poor conductors, often gases or brittle solids at room temperature.

✅ Metalloids: Properties between metals and non-metals; semiconductors (e.g. silicon used in computer chips).

⚛️ Part C: Atomic Structure — Model Description

Students should draw and describe the structure of a named element. Use the model below for Carbon (C, atomic number 6) as a marking reference.

A central nucleus clearly labelled
6 protons (positive charge) shown in the nucleus
6 neutrons (neutral charge) shown in the nucleus
6 electrons arranged in shells (2 in the first shell, 4 in the second shell)
Shells/orbits drawn around the nucleus with electrons labelled

✅ "Carbon has an atomic number of 6, meaning it has 6 protons in its nucleus and 6 electrons orbiting in shells. The first electron shell holds 2 electrons and the second shell holds 4 electrons. The nucleus also contains 6 neutrons. Carbon is a non-metal and is found in all living things."

Marking note: Award full marks if the student correctly identifies the number of protons, electrons, and neutrons, and accurately describes the electron shell arrangement. Deduct marks if shells are incorrectly filled or the atomic number is confused with the mass number.