Radioactivity: Detection of Radioactivity

Rutherford fired alpha particles at thin gold foil. What did he observe?

• Most alpha particles bounced back or were deflected with very few passing straight through the foil
• Most alpha particles passed straight through the gold foil, some bounced back or were deflected.
• Most alpha particles passed through the gold foil but some stuck to the gold foil

Rutherford saw that most alpha particles passed straight through the gold foil. What did this prove?

• That electrons were on shells orbiting the nucleus
• That there was a positive nucleus in the atom
• That the atom was mostly empty space

Which part of Rutherford's atomic model is responsible for alpha particles bouncing back?

• Positive nucleus
• Electrons
• Neutral nucleus

What charge does an alpha particle have and why was it bounced back /  deflected from the nucleus?

• An alpha particle is positive and repelled the positive nucleus as opposite charges repel.
• An alpha particle is positive and repelled the positive nucleus as like charges repel.
• An alpha particle is negative and repelled the positive nucleus as like charges repel.

What does the number 12 represent in the diagram?

• Mass number: the number of neutrons
• Mass number: number of neutrons and protons
• Mass number: the number of protons

What is an isotope?

• Atoms of the same element that have the same number of protons and electrons but different numbers of neutrons.
• Atoms of different elements that have the same number of protons and electrons but different numbers of neutrons.
• Atoms of the same element that have the same number of neutrons and electrons but different numbers of protons

Isotopes of the same element have...

• Different mass numbers because they have different numbers of electrons
• different mass numbers because they have different numbers of neutrons
• Different atomic numbers because they have different numbers of protons.

Atoms are neutral because they have ...

• equal numbers of positively charged protons and negatively charged electrons and their charges cancel each other out.
• equal numbers of positively charged neutrons and negatively charged electrons and their charges cancel each other out
• equal numbers of positively charged protons and negatively charged neutrons and their charges cancel each other out

How does an atom become a positive ion?

• The atom loses electrons.
• The atom gains electrons
• The atom loses protons

What is background radiation?

• The ionising radiation that is around us all the time
• The ionising radiation from naturally occurring radiation
• The ionising radiation that is from human activities