Unit 1 - Matter and Chemical Bonding

Question 1

Uniform composition

Answer 1

same ratio all throughout

Question 2

Homogenous mixture

Answer 2

• visibly indistinguishable components (has uniform composition)
• salt water

Question 3

Heterogeneous mixture

Answer 3

• visibly distinguishable components
• oil and vinegar

Question 4

Matter is categorized as ____ or _____

Answer 4

pure substances and mixtures

Question 5

Pure substances can be categorized as ____ or ____

Answer 5

elements and compounds (can only be separated into its original elements through chemical reactions)

Question 6

Mixtures can be categorized as ____ or ____

Answer 6

heterogeneous or homogenous

Question 7

Methods of Separation

Answer 7

Distillation

Filtration

Centrifugation

Chromatography

Question 8

Distillation

Answer 8

• Process that depends heavily on differences in volatility of component
• Ideal for separating liquids from solid in homogenous
• Good for separating 2 liquids with different boiling points

Question 9

Filtration

Answer 9

• Separating solid from liquid in heterogeneous
• Can be carried out by gravity of partial vacuum

Question 10

Centrifugation

Answer 10

• separation of insoluble materials from a liquid where normal filtration does not work
• Based on size, shape, density of particles, this viscosity of medium and speed of rotation
• Denser particles are forced to bottom and later one stay at the top when spun rapidly

Question 11

Chromatography

Answer 11

• Separation method using mobile (solvent, gas or liquid) and stationary phase (solid)
• Component with a high affinity for mobile phase moves more quickly through the system

Question 12

The word atom comes from the Greek word ____ meaning ____.

Answer 12

The word atom comes from the Greek word “__atomos__” meaning indivisible

Question 13

Democritus and Leucippus

Answer 13

(460-370 B.C.)

Expressed the belief that matter is composed of very small, indivisible particles, atomos (later known as atoms). They had, however, no way of testing their ideas.

Question 14

In___ an English scientist, ___ ___ formulated a precise definition of the indivisible building blocks of matter, which we call atoms.

Answer 14

In 1809 an English scientist, John Dalton formulated a precise definition of the indivisible building blocks of matter, which we call atoms.

Question 15

Dalton’s Atomic Theory

Answer 15

• All matter is made up of small particle called atoms that can’t be broken further (not including subatomic particles)
• The atoms of one element must all have same mass and size. (doesn’t know about isotopes yet)
• atoms of different elements combine in whole # ratios to make compound (Law of definite proportion)
• In chemical reactions, atoms are not changed; rather, they are reorganized. (Law of conservation of mass).

Question 16

Uniform Composition

Answer 16

Same ratio throughout

Question 17

JJ Thomson’s Atomic Model (the plum pudding model)

Answer 17

• described composition of atom (late 19th to early 20th century)
• ray in cathode-ray tube was coming out from -ve side of conductor
• ray is beam of electrons
• assumed that electrons lay in a cloud of positively charged particles

Question 18

Ernest Rutherford Atomic Model

Answer 18

1911

• decided to test Thomson’s model and shot alpha particles that are +vely charged at a thin gold sheet
• if it followed Thomson all the rays would shoot straight through
• many particles deflected at large angles
• reasoned that the angels were caused by a centre of concentrated positive charge that contains most of the atomic mass

alpha particle is nucleus (2n and 2p)

Question 19

Neils Bohr Atomic Model

Answer 19

1913

• was Danish
• developed model for atom
• protons and neutrons form nucleus, not in it
• electrons are lighter than protons
• Coulombs charge of electron
• P+E have same magnitude but opposite, that’s why they are relative

Question 20

Electron Cloud

Answer 20

electrons at different spots at different instances, can not follow path of electrons