2.1.1 Atomic structure and isotopes

Question 1

What is the definition of an isotope ?

Answer 1

isotopes are atoms of the same element with different numbers of neutrons meaning they have different masses (mass numbers) but the atomic number stays the same.

Question 2

Explain what is meant by an relative atomic mass of an element. (2)

Answer 2

mean/average mass of an atom ✓ (1)

compared with 1/12th mass of carbon-12
OR compared with mass of carbon-12 which is 12 ✓(2)

Question 3

State the similarities and differences between the atomic structure of isotopes of the same element.(2)

Answer 3

(Same) number of protons AND electrons ✓(1)

Differences: (Different) number of neutrons ✓(2)

Question 4

How do we calculate the maximum number of electrons that can orbit a shell.

Answer 4

Question 5

What was stated in Dalton’s atomic theory ? (4)

Answer 5

• Atoms are tiny particles made of elements
• Atoms cannot be divided
• All the atoms in an element are the same
• Atoms of one element are different to those of other elements.

Question 6

What did Thompson discover about electrons ? (3)

Answer 6

• They have a negative charge
• They can be deflected by magnet and electric field.
• They have very small mass

Question 7

Explain the plum pudding model

Answer 7

Atoms are made up of negative electrons moving around in a sea of positive charge.

Question 8

What were Rutherford’s proposal after the gold leaf experiment (4)

Answer 8

• Most of the mass and positive charge of the atom are in the nucleus.
• Electrons orbit the nucleus
• Most of atom’s volume is the space between the nucleus and the electrons.
• Overall positive and negative charges must balance

Question 9

Explain the current model of the atom

Answer 9

• Protons and neutrons are found in the nucleus.
• Electrons orbit in shells
• Nucleus is tiny compared to the total volume of the atom
• Most of the atom’s mass is in the nucleus
• Most of the atom is empty space between the nucleus and the electrons.

Question 10

What does the atomic number tell about an element ?

Answer 10

Atomic number = Number of protons in an atom.

Question 11

How do we calculate atomic mass

Answer 11

Mass number = Number of protons + Number of neutrons.

Question 12

Different isotopes in the same group or of the same element (e.g antimony) have the same chemical properties

Answer 12

same number of electrons in outer shell (or on the same arrangement).
OR
same electron configuration OR electron structure ✔

Question 13

What is the unit used to measure atomic masses

Answer 13

Unified atomic mass unit, U.

Question 14

What is the unit of relative atomic mass.

Answer 14

No units.