Unit 1: Structures & Properties Of Matter

Question 1

What is chemistry

Answer 1

The study of matter, its properties and changes

Question 2

What is matter

Answer 2

Anything that has mass and takes up space

Question 3

List people of the atomic theory

Answer 3

Greek philosophers
Democritus
Alchemists
Robert Boyle, Joseph Proust, Antonio Lavoisier 
John Dalton
JJ Thomson
William Crooks, Eugene Goldstein, Henri Becquerel and Marie Currie
Ernest Rutherford

Question 4

Explain Greek Philosophers contribution to atomic theory

Answer 4

All matter was composed of four elements: earth, air, fire and water

Question 5

Democritus contribution to atomic theory

Answer 5

Proposed first theory. Matter could be divided into tiny particles called atoms (atomos means indivisible).

Question 6

Alchemists contribution to atomic theory

Answer 6

Searching for a substance that would turn metals to gold, or the elixir of life that granted eternal life.

Question 7

Robert Boyle, Joseph Proust and Antoine Lavoisier contributions to atomic theory.

Answer 7

Boyle - defined elements as simplest substances
Proust - law of definite proportions
Lavoisier - law of conservation of mass

Question 8

John dalton contribution to atomic theory

Answer 8

1. Matter is made up of tiny indivisible particles called atoms
2. All atoms of a particular element are identical in mass, size and other properties.
3. Atoms of different elements have different characteristics such as size and mass.
4. Atoms of different elements combine in small, while number ratios to form compounds.
5. In chemical reactions, atoms are neither created nor destroyed but simply rearranged

Question 9

JJ Thomson contribution to atomic theory.

Answer 9

Discovered electron.
In cathode ray tubes, electrical current is supplies from negative electrode and travels to positive electrode. Cathode rays curve away from magnets as negative charges would. Concluded that cathode rays are a stream of negatively charged particles, electrons.
Raisin bun model - atom has positively charged dough with negatively charged raisins embedded in it.

Question 10

William Crooks, Eugene Goldstein, Henri Becquerel and Marie Currie contributions to atomic theory.

Answer 10

Crooks - discovered electron. Charge -1, mass = 0.00055 u
Goldstein - discovered proton. Charge +1, mass = 1.007 u
Becquerel and Currie - radioactivity

Question 11

Ernest Rutherford contribution to atomic theory

Answer 11

Had a radioactive sample emit beams through gold foil. Most particles went through and hit zinc silfide screen, but some bounced back.

1. Matter is made of mostly empty space
2. Most of the mass and he positive charge are in centre or nucleus
3. Electrons orbit the nucleus at a relative far distance

Question 12

What is the problem with Rutherford’ model?

Answer 12

According to physics, as an object accelerates, it emits energy, meaning the electrons moving around the body would lose energy and collapse. This does not happen.

Question 13

What is quanta?

Answer 13

Small bursts of energy

Question 14

What was einstein’s photoelectric effect?

Answer 14

1. Light consists of a stream of quanta called photons
2. The release of electrons from a metal surface can be explained by a photon - electron collision, in which the energy of the photon is transferred to the electron
3. There is a min amount of photon energy required by the electron to be able to escape from the atom

Question 15

Bohr’s explanation of H’s line spectrum

Answer 15

1. Electrons exist in circular orbits. They are held in place by electrostatic forces between the pos nucleus and neg electrons.
2. If the energy (light) released or absorbed by an atom can be quantized, so can the energy of the electrons. Consequently, electrons can only exist in certain energy levels.
3. Electrons do not emit energy as they orbit the nucleus.
4. Electrons can jump from one orbit to another. When it is higher than its ground state, it is in excited state. Transitioning to a lower energy level causes the release of a photon of light. Causes spectral lines.

Question 16

How can electrons absorb energy and become excited according to Bohr?

Answer 16

1. Colliding with a highly energetic particle, like an electron in an electric current passing through a gas
2. The atom can absorb a photon that has an amount of energy equal to the difference between the energy of the orbit it occupies and the energy of a higher orbit.

Question 17

What was the problem with Bohr’s model?

Answer 17

Did not explain the line spectra of atoms with two+ electrons

Question 18

What did Louis de Broglie reason?

Answer 18

If light waves have some properties of particles, then particles must have some properties of waves.

Question 19

What is the Heisenberg Uncertainty Principle?

Answer 19

It’s impossible to determine both an electron’s position and momentum at the same time. Any attempt to measure one will interfere with the other.

Question 20

Explain the quantum numbers.

Answer 20

N - principal quantum number
Determines energy of the electron
As many as 2n^2 electrons can be found in any energy level

L - angular momentum quantum number
Sub levels
N-1
0: s, 1:p, 2:d, 3:f

M/ml - magnetic quantum number
Indicates orientation in space of the orbital shape.
Ranges from -L to +L

Ms/s - electron spin magnetic quantum number
+1/2 or -1/2

Question 21

What is the Pauli Exclusion Principle?

Answer 21

No two electrons can have the same set of quantum numbers

Question 22

What is the Aufbau principle?

Answer 22

When filling orbitals, electrons must be placed into the lowest possible energy level

Question 23

What is Hund’s rule?

Answer 23

Electrons in the same sub-level or orbital will not pair up until all orbitals in that sub level have been half filled. The unpaired electrons will have the same spin value.

Question 24

What are the electron configuration exceptions?

Answer 24

All elements in groups 6 and 11

Question 25

Atomic structure and the periodic table

Answer 25

1. For main group elements, the last numeral of the group number is the number of valence electrons
2. The n value of the highest occupied energy level is the period number
3. The square of n is equal to total orbitals in energy level.