Chapter 2

Question 1

Brownian motion

Answer 1

the particle motion was the result of the molecular bombardments of the particles due to the thermal energy of the surrounding water

Question 2

Atomic Theory

Answer 2

1. each element is composed of tiny, indestructible particles called atoms
2. all atoms of a given element have the same mass and other properties that distinguish them from the atoms of other elements
3. atoms combine in simple whole-number ratios to form compounds
4. atoms of one element cannot change into atoms of another element. In a chemical reaction, atoms only change the way they are bound together with other atoms

Question 3

Law of conservation of mass

Answer 3

in a chemcial reaction, the matter is neither created nor destroyed

Question 4

Law of Multiple proportions

Answer 4

when two elements (A and B) form two different compounds, the masses of element B that combine with 1g of element A can be expressed as a ratio of small whole numbers

Question 5

Law of Definite Proportions

Answer 5

all samples of a given compound, regardless of their source or how they were prepared, have the same proportions of their constituent elements

Question 6

Nuclear theory

Answer 6

1. most of the atom’s mass and all of its positive charge are contained in a small core called the nucleus
2. most of the volume of the atom is empty space, throughout which tiny, negatively charged electrons are dispersed
3. there are as many negatively charged electrons outside the nucleus as there are positively charged particles (protons) within the nucleus, so the atom is electrically neutral

Question 7

Atomic number (Z)

Answer 7

number of protons in an atom’s nucleus
- The top number

Question 8

Mass number (A)

Answer 8

sum of number of neutrons and protons

Question 9

cation

Answer 9

positively charged

Question 10

anion

Answer 10

negatively charged

Question 11

Atomic mass

Answer 11

the average mass of the isotope that compose that element, weighted according to the natural abundance of each isotope
Sum of the (fraction of isotope n) x (mass of isotope n)

Question 12

metals

Answer 12

good conductors of heat electricity, they can be pounded into flat sheets, drawn into wires, shiny, lose electrons when they undergo chemical changes

Question 13

Nonmetal

Answer 13

poor conductors of heat and electrically, tend to gain electrons when they undergo chemical change

Question 14

metalloids

Answer 14

semiconductors, highly temperature dependent

Question 15

Noble gas

Answer 15

mostly unreactive

Question 16

Alkali metals

Answer 16

all reactive metals

Question 17

Alkali Earth metals

Answer 17

fairly reactive, not as reactive as alkali metals

Question 18

Halogens

Answer 18

very reactive nonmetals

Question 19

In a chemical reaction what tends to become a cation and what an anions

Answer 19

metals lose electrons -> cations
nonmetals gain electrons -> anions

Question 20

mole

Answer 20

6.022 x 10^23