unit 2 topic 1-3

Question 1

chemistry

Answer 1

a branch of science that deals with the composition and properties of substance and various forms of matter.

Question 2

caustic

Answer 2

capable of burning, corroding or destroying living tissue.

Question 3

Homogenous

Answer 3

when the particles in a mixture are uniformly scattered

Question 4

Heterogenous

Answer 4

when the particles in a mixture are NOT uniformly scattered.

Question 5

Physical change

Answer 5

occurs when a substance changes form, but NOT chemical composition

Question 6

chemical change

Answer 6

occurs when one or more NEW. substances are formed from a chemical reaction

Question 7

Law of conservation of mass

Answer 7

in a chemical change, the total mass of the new substance is always the same as the total mass of the original substances.

Question 8

Law of definite composition

Answer 8

compounds are pure substances that contain two or more elements combined together in fixed proportions

Question 9

electrolysis

Answer 9

the process of decomposing a chemical compound by passing an electric current through it

Question 10

element

Answer 10

a pure substance made up of only one type of particle

Question 11

compounds

Answer 11

a pure substance made up of two or more elements chemically combined together

Question 12

electrons

Answer 12

negatively charged particles

Question 13

atomic nucleus

Answer 13

the centre of the atom contains the protons and neutrons.

Question 14

proton

Answer 14

positively charged particles

Question 15

neutrons

Answer 15

neutral ( uncharged) particles

Question 16

the particle model of matter

Answer 16

• all matter is made up of extremely tiny particles
• each pure substance has its own kind of particle, different from the particles of other pure substances.
• particles attract each other.
• particles are always moving
• particles at a higher temperature move faster on average than particles at a lower temperature

Question 17

matter

Answer 17

anything that has a mass and takes up space

Question 18

mixture

Answer 18

is a substance made by combining two or more different materials together

Question 19

solutions

Answer 19

a homogenous mixture of two or more substances

Question 20

suspensions

Answer 20

a heterogeneous mixture in which particles settle slowly after mixing

Question 21

colloid

Answer 21

a heterogenous mixture composed of fine particles evenly distributed throughout a second substance

Question 22

what is emulsions

Answer 22

types of colloids in which liquids are dispersed in liquids

Question 23

quantitative physical properties

Answer 23

a characteristic of a substance that can be measured numerically (a quantity)

Question 24

qualitative physical properties

Answer 24

a characteristic of a substance that can be described but not measured numerically

Question 25

density

Answer 25

amount of matter that occupies a certain space; the mass per unit volume of a substance

Question 26

combustibility

Answer 26

is a measure of how easily a substance bursts into flame, through fire fire or combustion.

Question 27

melting point

Answer 27

the temperature at which a solid changes to a gas

Question 28

what is a boiling point

Answer 28

the temperature at which a water turns into a gas

Question 29

what is precipitate

Answer 29

is a solid that forms as the result of a chemical reaction or leftovers

Question 30

daltons atomic theory

Answer 30

states that all mater is made up of small particles called atoms. Atoms cannot be created, destroyed, or divided into small particles.

Question 31

what is one thing that Daltons atomic theory states

Answer 31

all atoms of the same element are identical in mass and size.
Atoms in one element are different in mass and size form atoms of another element.

Question 32

what does Daltons theory state about compounds

Answer 32

they are created when atoms of different elements link together in definite proportions

Question 33

what is Thomson’s plum pudding atomic model

Answer 33

he discovered that atoms are composite objects made of pieces with positive and negative charge and that the negatively charged elections within the atom were very small compared to the entire atom.

Question 34

Rutherford solar system atomic model

Answer 34

he said that the positive charges and mass of the atom are concentrated in the centre of the atom or nucleus
2. negatively charges particles moving rapidly around the nucleus

Question 35

what is the bohr’s atomic model state

Answer 35

electrons are arranged in definite energy levels

2. elections follow a prescribed orbit around the nucleus
3. electrons may be dislodged from orbits (energy levels) when they absorb or release energy

Question 36

what is the election cloud mode l

Answer 36

1. electrons has a wave-like properties
2. electrons exist in definite exist in definite energy levels
3. location of the electron is uncertain, it is described in terms of the probability of being fed in a cartoon region of space around the nucleus
4. these regions of space are called orbitals.

Question 37

what is the Billiard Ball model

Answer 37

1. smallest particle of mater (Atom)
2. for a given substance atoms are identical in size, shape and mass
3. smallest part of an element that can take part in chemical change and combine in whole numbers.
4. atom is indivisible, unchangeable and indestructible