Developing Atomic Theories

Question 1

Dalton’s Atomic Theory(1766-1844)

Answer 1

• All matter is made up of small particles called atoms.
• Atoms cannot be created, destroyed or divided into smaller atoms.
• All atoms of the same element are identical in mass and size, but they are different in mass and size from atoms of other elements.
• Compounds are formed when atoms of different elements combine in fixed proportions. The tiniest particles of any compound always contain the same types and relative number of atoms.

Question 2

J.J. Thomson(1856-1940)
What did he find?
Draw and label his model.
What is the model name?

Answer 2

He found out that there were bodies smaller than an atom and were negatively charged.
A circle with dots inside it. Dots = electrons. Circe = Positively charged sphere.
Plum-pudding or raisin bun.

Question 3

Rutherford’s Atomic Model(1871-1937)

What was his model called?

Answer 3

Planetary

Question 4

Define nucleus.

Answer 4

A central region that is positively charged, extremely small and contains almost all of the atom’s mass.

Question 5

Define electrons.

Answer 5

Particles with a negative charge at the outer region of the atom. The electron is smaller than protons and neutrons.

Question 6

Define empty space.

Answer 6

The volume of space around the nucleus is very large. Electrons exist there but it is mostly empty.

Question 7

Define neutron.

Answer 7

A subatomic particle with the same mass as a proton without the electrical charge.

Question 8

Define isotopes.

Answer 8

Atoms of the same element differ in mass but are chemically alike.

Question 9

Niel Bohr(1885-1962)
Define energy levels.
Describe his diagram.

Answer 9

A fixed amount of energy that an electron can have.
A nucleus that’s surrounded by rings that represent the energy levels. The rings can have dots(electrons) that represent the number of electrons on the level corresponding with its atom.

Question 10

How many electrons can be in the first energy level?

Answer 10

2

Question 11

How many electrons can be in the second energy level?

Answer 11

8

Question 12

The evolved atomic theory.

Answer 12

The electron energy levels are now thought to be divided into sublets. Electrons in the same energy level are grouped in pairs. Neutrons and protons are made of particles called quarks. Now there are dozens of fundamental particles instead of three subparticals.

Question 13

The word atom comes from the Greek word meaning _______.

Answer 13

Uncuttable.

Question 14

Atoms consist of what subatomic particles?

Answer 14

Protons, Neutrons, and electrons.

Question 15

What are the symbol, charge, relative mass and locations of a proton?

Answer 15

p^+, 1+, 1.67 X 10^-24, and 10^-15.

Question 16

What are the symbol, charge, relative mass and locations of a neutron?

Answer 16

n^degree, 0, 1.67 X 10^-24, 10^-15.

Question 17

What are the symbol, charge, relative mass and locations of an electron?

Answer 17

e^-, 1-, 9.02 X 10^-28, smaller than 10^-18.

Question 18

Atoms of different elements have different numbers of ______, _______ and _______.

Answer 18

protons, neutrons and electrons.

Question 19

The size of the nucleus is ______ compared to the size of the atom, but the mass of the nucleus is _________ to the mass of the entire atom.

Answer 19

Really small, massive compared.

Question 20

An atom is electrically _____ because the number of electrons is equal to the number of protons.

Answer 20

Neutral.