S.1.2.1 and S.1.2.2 The Atomic Model and Isotopes

Question 1

Dalton’s atomic model

Answer 1

• All matter is made up of indivisible particles called atoms
• Atoms cannot be created or destroyed
• Atoms of the same element are alike in every way
• Atoms of different elements are different
• Atoms can combine in small numbers to form molecules

Some parts of this model are incorrect

Dalton’s theory was rejected at first

Question 2

J.J. Thomson’s plum pudding model

Answer 2

Electrons; charged particles are evenly distributed within the atom; atoms are dense like pudding

Some parts of this model are incorrect

Question 3

Alpha particle

Answer 3

Two protons and two neutrons

2+ charge

Question 4

Ernest Rutherford’s Gold Foil Experiment

Answer 4

Positively charged alpha particles shot through a thin sheet of gold foil; planetary model of the atom

Question 5

Nearly all the alpha particles went straight through the foil

Answer 5

The nucleus is very small in comparison to the size of the atom

Key factor of the nucleus

Question 6

Some of the alpha particles bounced straight back

Answer 6

The nucleus is very dense, containing virtually all the mass of the atom

Key factor of the nucleus

Question 7

Alpha particles are repelled when closely approaching the nucleus

Answer 7

The nucleus has a positive charge

Key factor of the nucleus

Question 8

Nucleons

Answer 8

Protons and neutrons

Can be further divided into quarks

Question 9

Subatomic particles

Answer 9

Nucleons and electrons

Question 10

Positron

Answer 10

Antiparticle of an electron

Question 11

Proton relative mass and charge

Answer 11

Relative mass of 1; relative charge of +1

Question 12

Electron relative mass and charge

Answer 12

Relative mass of 0.0005; relative charge of -1

Question 13

Neutron relative mass and charge

Answer 13

Relative mass of 1; no charge

Question 14

Ion

Answer 14

Electrons are responsible for chemical change

Question 15

Isotopes

Answer 15

Atoms of the same element with different numbers of neutrons

Question 16

Chemical and physical properties of isotopes

Answer 16

Chemical properties are same for all isotopes of the same element; physical properties change for different isotopes

Question 17

Chemical properties of atoms

Answer 17

Chemical stability, heat of formation, flammability

How particles interact; determined by electron configuration

Question 18

Physical properties of atoms

Answer 18

Boiling point, melting point, density, and rate of diffusion

Question 19

Relative abundance

Answer 19

Percentage of atoms with a specific mass number in a naturally occurring sample of the element