An atom is the basic building block of all matter. It consists of a tiny, positively charged nucleus surrounded by orbiting, negatively charged electrons .

The nucleus is the central part of an atom. It is made up of positively charged protons and neutrally charged neutrons , making the overall nucleus positively charged.

An ion is an electrically charged atom (or group of atoms) formed by the loss or gain of electrons.

Describe the method used in Rutherford's alpha particle scattering experiment.

A beam of alpha particles was directed at a thin sheet of gold foil .

How are positive and negative ions formed?

Positive ions form when an atom loses electrons (more protons than electrons). Negative ions form when an atom gains electrons (more electrons than protons).

State the three key observations of Rutherford's alpha particle scattering experiment.

Most alpha particles passed straight through the foil Some were deflected through small angles A very small number were deflected straight back

What is the proton number of an atom, and what does it determine?

The proton number (or atomic number) is the number of protons in an atom's nucleus. It determines which element the atom is.

Why did most alpha particles pass straight through the gold foil?

Because the atom is mainly empty space .

What is the nucleon number of an atom?

The nucleon number (or mass number) is the total number of protons and neutrons in an atom's nucleus.

Why were a very small number of alpha particles deflected straight back?

Because the nucleus is extremely small .

Some alpha particles are deflected through small angles because the positive alpha particles are repelled by the ______ , which contains most of the atom's mass.

Some alpha particles are deflected through small angles because the positive alpha particles are repelled by the positive nucleus , which contains most of the atom's mass.

In nuclide (ZAX) notation, the top number A represents the ______ number, equal to the total protons and neutrons in the nucleus.

In nuclide (ZAX) notation, the top number A represents the nucleon number, equal to the total protons and neutrons in the nucleus.

True or False? Alpha particles used in Rutherford's experiment are positively charged.

True. Alpha particles have a charge of +2 , which is why they are repelled by the positive nucleus.

Isotopes are atoms of the same element with an equal number of protons but a different number of neutrons .

True or False? Isotopes tend to be more stable than non-isotope atoms of the same element.

False. Isotopes tend to be more unstable , due to their imbalance of protons and neutrons, making them more likely to decay .

O LevelPhysicsCambridge (CIE)Flashcards5. Nuclear Physics5.1 The Nuclear Model of the Atom

5.1 The Nuclear Model of the Atom (Cambridge (CIE) O Level Physics): Flashcards

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Cards in this collection (17)

Define atom.
An atom is the basic building block of all matter. It consists of a tiny, positively charged nucleus surrounded by orbiting, negatively charged electrons.
Define nucleus.
The nucleus is the central part of an atom. It is made up of positively charged protons and neutrally charged neutrons, making the overall nucleus positively charged.
Who carried out the alpha particle scattering experiment that led to the nuclear model of the atom, and in which year?
Ernest Rutherford, in 1909.
Define ion.
An ion is an electrically charged atom (or group of atoms) formed by the loss or gain of electrons.
Describe the method used in Rutherford's alpha particle scattering experiment.
A beam of alpha particles was directed at a thin sheet of gold foil.
How are positive and negative ions formed?
Positive ions form when an atom loses electrons (more protons than electrons). Negative ions form when an atom gains electrons (more electrons than protons).
State the three key observations of Rutherford's alpha particle scattering experiment.
- Most alpha particles passed straight through the foil
- Some were deflected through small angles
- A very small number were deflected straight back
What is the proton number of an atom, and what does it determine?
The proton number (or atomic number) is the number of protons in an atom's nucleus. It determines which element the atom is.
Why did most alpha particles pass straight through the gold foil?
Because the atom is mainly empty space.
What is the nucleon number of an atom?
The nucleon number (or mass number) is the total number of protons and neutrons in an atom's nucleus.
Why were a very small number of alpha particles deflected straight back?
Because the nucleus is extremely small.
How is the number of neutrons in an atom calculated?
$Number of neutrons = Nucleon number - Proton number$
where the nucleon number (A) is the total protons and neutrons, and the proton number (Z) is the number of protons.
Some alpha particles are deflected through small angles because the positive alpha particles are repelled by the ______, which contains most of the atom's mass.
Some alpha particles are deflected through small angles because the positive alpha particles are repelled by the positive nucleus, which contains most of the atom's mass.
In nuclide (ZAX) notation, the top number A represents the ______ number, equal to the total protons and neutrons in the nucleus.
In nuclide (ZAX) notation, the top number A represents the nucleon number, equal to the total protons and neutrons in the nucleus.
True or False?
Alpha particles used in Rutherford's experiment are positively charged.
True.
Alpha particles have a charge of +2, which is why they are repelled by the positive nucleus.
Define isotopes.
Isotopes are atoms of the same element with an equal number of protons but a different number of neutrons.
True or False?
Isotopes tend to be more stable than non-isotope atoms of the same element.
False.
Isotopes tend to be more unstable, due to their imbalance of protons and neutrons, making them more likely to decay.

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