2.2

Atomic structure

12 flashcards to master Atomic structure

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Definition Flip

Describe the structure of an atom.

Answer Flip

An atom consists of a central nucleus containing protons and neutrons, surrounded by electrons in shells (energy levels).

Key Concept Flip

Answer Flip

Key Concept Flip

2.2 Atomic structure: What are the relative masses of a proton, neutron, and electron?

Answer Flip

Protons and neutrons have a relative mass of 1. Electrons have a negligible mass compared to protons and neutrons; its relative mass is approximately 1/1836. The actual mass of an electron is approximately 9.11 × 10⁻³¹ kg, demonstrating it is not truly massless but significantly smaller than the mass of a proton or neutron.

Definition Flip

Define proton number (atomic number).

Answer Flip

The proton number is the number of protons in the nucleus of an atom. It uniquely identifies an element.

Example: Hydrogen has 1 proton.
Definition Flip

Define mass number (nucleon number).

Answer Flip

The mass number is the total number of protons and neutrons in the nucleus of an atom.

Example: Oxygen-16 has a mass number of 16.
Key Concept Flip

What is the electronic configuration of Potassium (proton number 19)?

Answer Flip

The electronic configuration of Potassium (K) is 2,8,8,1.

Key Concept Flip

Topic: 2.2 Atomic structure Question: What is the electronic configuration of the Oxide ion (O²⁻, Oxygen has proton number 8)?

Answer Flip

An oxygen atom has electronic configuration 2,6. An O²⁻ ion has gained 2 electrons to achieve a full outer shell, similar to the noble gas Neon. Therefore, the electronic configuration of the oxide ion is 2,8.

Key Concept Flip

What is the electronic configuration of Sodium (Na, proton number 11)

Answer Flip

The electronic configuration of Sodium (Na) is 2,8,1.

Key Concept Flip

Answer Flip

Key Concept Flip

How is the number of outer shell electrons related to the group number (Groups I to VII)?

Answer Flip

The number of outer shell electrons is equal to the group number.

Example: Sodium (Group I) has 1 outer shell electron.
Key Concept Flip

How is the number of occupied electron shells related to the period number?

Answer Flip

The number of occupied electron shells is equal to the period number.

Example: Sodium (Period 3) has 3 occupied electron shells (2,8,1).
Definition Flip

What are isotopes?

Answer Flip

Atoms of the same element with the same proton number but different mass numbers.

Example: Carbon-12 and Carbon-14 both have 6 protons, but C-12 has 6 neutrons while C-14 has 8.

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2.1 Elements, compounds and mixtures 2.4 Structure and properties

Key Questions: Atomic structure

Describe the structure of an atom.

An atom consists of a central nucleus containing protons and neutrons, surrounded by electrons in shells (energy levels).

Define proton number (atomic number).

The proton number is the number of protons in the nucleus of an atom. It uniquely identifies an element.

Example: Hydrogen has 1 proton.
Define mass number (nucleon number).

The mass number is the total number of protons and neutrons in the nucleus of an atom.

Example: Oxygen-16 has a mass number of 16.
What are isotopes?

Atoms of the same element with the same proton number but different mass numbers.

Example: Carbon-12 and Carbon-14 both have 6 protons, but C-12 has 6 neutrons while C-14 has 8.

About Atomic structure (2.2)

These 12 flashcards cover everything you need to know about Atomic structure for your Cambridge IGCSE Chemistry (0620) exam. Each card is designed based on the official syllabus requirements.

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