Chapter 2 Test

Question 1

Law of definite proportions

Answer 1

A chemical compound has a ratio of specific atoms that never changes

Question 2

Multiple proportions

Answer 2

Two elements can join up in more than one way.
Like CH2 and CH4
Ratio of oxygen is 1:2 since 4 is double the small. Big / small = ratio

when two elements combine with each other to form more than one compound, the weights of one element that combine with a fixed weight of the other are in a ratio of small whole numbers

Question 3

Conservation of mass

Answer 3

Más cannot be created or destroyed

Question 4

Postulates of daltons theory

Answer 4

John dalton’s Atomic Theory is the idea that
1) all matter is composed of atoms, tiny, indestructible particles.
2) Atoms of the same molecules have the same properties, including mass.
3) Atoms of one element cannot change to atoms of another element, nor can atoms be destroyed. During chemical experiments, atoms can only change how they are bound together.
4) Atoms combine in simple, whole numbered ratios to form chemical compounds.

Question 5

Discovery of electron

Answer 5

Thompson discovered the electron using the cathode ray tube. The cathode rays were attracted to the to the positively charged elctorde, meaning that they were composed of negatively charged particles which we now know as electrons. Plum
Pudding model

Question 6

Discovery of neutron

Answer 6

Chadwick discovered the neutron and that neutrons account for the rest of the mass of an atom.

Question 7

Discovery of nucleus

Answer 7

Rutherford’s gold foil experiment. He send positively charged alpha particles at a piece of gold foil. Most passed through, but some bounced back, meaning that atoms have a small and dense positively charged nucleus because positive particles were being rejected, and this nucleus had to be small so that the other alpha particles could pass through. Most of an atom is empty space, this is the volume. Discovered that the nucleus has protons and believed there to be as many protons as electrons. “Nuclear model” electrons around “dense positive center”.

Question 8

Discovery of Mass to charge ratio of electrons

Answer 8

Millikan measured the strength of an electric field needed to stop the free fall of negatively charged oil droplets (stripped down to electrons). He then found mass of drops and calculated charge of each drop. Discovered each drop must have whole number of electrons. Charge must be multiple of an electrons charge (-1.y0 x 10^-19 C). Plum pudding

Question 9

Groups on periodic table

Answer 9

1a is alkali metals
2a is alkaline earth metals
7A is halogens
8a is noble gases
Most tall sides are main group (representative)
Middle sections is sptransition metals
Period 1 starting with Hydrogen
Floating rows is inner transition metals
Left of ladder is metals
Right of latter is nonmetals (plus H)
On latter (except for Al) are metalloids
Columns have similar properties
Left to right for atomic number

Question 10

Facts on Metals

Answer 10

Good conductors
Malleable
Ductile (made into wire)
Lose e- (cations). Never gain, but don’t always loose
Solid at room temp

Question 11

Facts on Nonmetals

Answer 11

Bad conductors
Brittle
Mostly dull
Gain e- (anions)
Any state of matter at room temperature

Question 12

Hydrogen Facts

Answer 12

Can loose or gain electrons
Nonmetal
Alkali

Question 13

Cations vs Anion

Answer 13

Cations are positively charged since the lose electrons.
Anions are negatively charged since they gain electrons.