Atomic Structure Worksheet - GCSE - Intermediate

Atomic Structure worksheet for GCSE (Key Stage 4 / GCSE (Ages 14-16)). Intermediate level science practice, aligned to the UK National Curriculum. Print-ready with answer key included.

Science•Key Stage 4 / GCSE (Ages 14-16)•Atomic Structureintermediate

14 views

Inside the Atom: GCSE Atomic Structure

Key Stage 4 • Ages 14–16 • Intermediate

Name:

Date:

Score:

Instructions: Complete each activity using the information given and your knowledge of atomic structure. Show working for calculations and use precise scientific vocabulary; electron configurations are written as numbers of electrons in shells.

The Structure of an Atom

Answer each question in a clear sentence or with the requested particle name. Remember that atoms have a tiny, positively charged nucleus surrounded by electrons. Include charge and relative mass where relevant.

1. Name the two types of particle found in the nucleus.

2. State the relative charge of a proton and of a neutron.

3. Where are electrons found, and what is their relative charge?

4. An atom has 11 protons, 12 neutrons and 11 electrons. State its proton number and mass number.

Isotopes and Atomic Notation

Use proton number to identify the element and mass number to find the number of neutrons. For a neutral atom, the number of electrons equals the number of protons. Show your calculation where appropriate.

1. Calculate the number of neutrons in carbon-14. Carbon has proton number 6.

2. Chlorine-35 and chlorine-37 are isotopes. State what is the same and what is different about their atoms.

3. A sodium ion, ²³₁₁Na⁺, has 11 protons. State its numbers of neutrons and electrons.

4. Explain why isotopes of the same element have the same chemical properties.

Electron Configurations

For the first 20 elements, electrons fill shells in the pattern 2, 8, 8, 2. Write each configuration as comma-separated shell numbers, such as 2,8,1. For the ion question, account for the charge when finding its electron count.

1. Write the electron configuration of an atom of oxygen (proton number 8).

2. Write the electron configuration of an atom of aluminium (proton number 13).

3. An atom has the electron configuration 2,8,7. State its proton number and the number of electrons in its outer shell.

4. A magnesium atom forms Mg²⁺. A neutral magnesium atom has 12 electrons. Write the electron configuration of the ion.

How Atomic Models Changed

Use the word bank to complete the statements about the development of atomic models. Each word is used once. Connect each change to the evidence that led scientists to revise their model.

Word bank: Dalton, plum pudding, alpha-particle scattering, nuclear, Bohr, energy levels

1. The early solid-sphere model was proposed by ___.

2. J. J. Thomson’s model described electrons embedded in a positively charged sphere and became known as the ___ model.

3. In the gold-foil experiment, the unexpected deflection of some alpha particles was evidence from ___.

4. Rutherford used this evidence to propose a small, dense, positive ___ at the centre of the atom.

5. Bohr proposed that electrons occupy fixed ___.

Apply Your Atomic Structure Knowledge

Answer the exam-style questions using calculations and explanations where needed. For the last question, compare the evidence with the model it challenged and explain how the model changed.

1. An atom has mass number 27 and proton number 13. Calculate its number of neutrons.

2. A neutral atom has the electron configuration 2,8,2. State its proton number.

3. Describe the structure of an atom, including the relative masses and charges of its three subatomic particles. [6 marks]

4. Explain how the alpha-particle scattering experiment led to a change from the plum pudding model to the nuclear model. [4 marks]

Answer Key

Activity 1: 1. Protons and neutrons ; 2. Proton: +1; neutron: 0 ; 3. In shells/energy levels around the nucleus; charge −1 ; 4. Proton number 11; mass number 23

Activity 2: 1. 14 − 6 = 8 neutrons ; 2. Same number of protons (and electrons in neutral atoms); different numbers of neutrons and therefore different mass numbers ; 3. Neutrons: 12; electrons: 10 ; 4. They have the same electron configuration, including the same number of outer-shell electrons

Activity 3: 1. 2,6 ; 2. 2,8,3 ; 3. Proton number 17; 7 outer-shell electrons ; 4. 2,8

Activity 4: 1. Dalton ; 2. plum pudding ; 3. alpha-particle scattering ; 4. nucleus ; 5. energy levels

Activity 5: 1. 27 − 13 = 14 neutrons ; 2. 12 ; 3. Nucleus contains positively charged protons (relative mass 1) and neutral neutrons (relative mass 1); negatively charged electrons (relative mass 1/1836) occupy shells around the nucleus; atom is mostly empty space ; 4. Most alpha particles passed through, but a small number were deflected sharply or bounced back; this showed positive charge and most mass were concentrated in a tiny, dense nucleus, contradicting the spread-out positive charge of the plum pudding model