Where are protons, neutrons and electrons found?

Protons and neutrons are in the nucleus; electrons are in shells around it.

What is the atomic number?

The number of protons in the nucleus (symbol Z).

What is the mass number?

The number of protons plus neutrons in the nucleus (symbol A).

How do you find the number of neutrons?

Mass number minus atomic number (A - Z).

Why is an atom electrically neutral?

It has equal numbers of protons (+1) and electrons (-1), so the charges cancel.

Atoms of the same element with the same number of protons but different numbers of neutrons.

Why do isotopes of an element have the same chemical properties?

They have the same number of electrons.

Describe Thomson's plum pudding model.

A ball of positive charge with electrons embedded in it.

What did most alpha particles do in the gold foil experiment, and what does it show?

They passed straight through, so most of the atom is empty space.

What did the few alpha particles that bounced back show?

The positive charge and most of the mass are concentrated in a tiny, dense nucleus.

What did Bohr add to the model of the atom?

Electrons orbit the nucleus in fixed shells (energy levels).

Atomic structureIB MYP Physics: Flashcards

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Question

What are the relative charge and relative mass of a proton?

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What are the relative charge and relative mass of a proton?: Charge +1, mass 1.
What are the relative charge and relative mass of a neutron?: Charge 0, mass 1.
What are the relative charge and relative mass of an electron?: Charge -1, mass about 1/1840.
Where are protons, neutrons and electrons found?: Protons and neutrons are in the nucleus; electrons are in shells around it.
What is the atomic number?: The number of protons in the nucleus (symbol Z).
What is the mass number?: The number of protons plus neutrons in the nucleus (symbol A).
How do you find the number of neutrons?: Mass number minus atomic number (A - Z).
Why is an atom electrically neutral?: It has equal numbers of protons (+1) and electrons (-1), so the charges cancel.
What are isotopes?: Atoms of the same element with the same number of protons but different numbers of neutrons.
Why do isotopes of an element have the same chemical properties?: They have the same number of electrons.
Describe Thomson's plum pudding model.: A ball of positive charge with electrons embedded in it.
What did most alpha particles do in the gold foil experiment, and what does it show?: They passed straight through, so most of the atom is empty space.
What did the few alpha particles that bounced back show?: The positive charge and most of the mass are concentrated in a tiny, dense nucleus.
What did Bohr add to the model of the atom?: Electrons orbit the nucleus in fixed shells (energy levels).

Exam questions on Atomic structure

A teacher in Nairobi builds a model of a lithium atom for her class. Her atom has 3 protons and 4 neutrons and is electrically neutral.
State the number of electrons in the lithium atom and explain why the atom has no overall charge.2 marks
In 1909 Hans Geiger and Ernest Marsden, working with Ernest Rutherford, fired alpha particles at a very thin sheet of gold foil and counted where the particles ended up. Almost all of the alpha particles passed straight through. A very small number were deflected through large angles, and a very few bounced almost straight back.
Explain why a small number of the alpha particles were deflected through large angles.2 marks
A student compares three neutral atoms. Atom X has 6 protons and 6 neutrons. Atom Y has 6 protons and 8 neutrons. Atom Z has 7 protons and 7 neutrons.
Identify which two atoms are isotopes of the same element and justify your answer.3 marks

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Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).