Chapter 2 Concepts

Question 1

Postulates of Dalton’s atomic theory, which are still valid

Answer 1

(i) Each element is composed of extremely small particles called atoms. (true)
(ii) Atoms are indivisible. (false)
(iii) Atoms of a given element are identical. (false)
(iv) Atoms of different elements are different and have different properties. (true)

Question 2

Law of Constant Composition

Answer 2

In a given compound, the relative numbers and kinds of atoms are constant.

Question 3

Law of Conservation of Mass/Matter

Answer 3

The total mass of materials present after a chemical reaction is the same as the total mass present before the reaction.

Question 4

Atomic number (Z)

Answer 4

Number of protons or electrons

Question 5

Atomic number/Mass number (A)

Answer 5

Number of protons plus neutrons

Question 6

What is an isotope?

Answer 6

Atoms with identical atomic numbers but different masses (same number of protons, but different number of neutrons).

Question 7

Explain the method for finding the atomic mass, using using fractional abundance & atomic mass for the isotopes

Answer 7

Multiply the abundance of each isotope by its atomic mass and sum each of the products. (Convert % abundance to decimal)

Question 8

Name of Periodic Table Group 1A

Answer 8

Alkali metals

Question 9

Name of Periodic Table Group 2A

Answer 9

Alkaline earth metals

Question 10

Name of Periodic Table Group 6A

Answer 10

Chalcogens

Question 11

Name of Periodic Table Group 7A

Answer 11

Halogens

Question 12

Name of Periodic Table Group 8A

Answer 12

Noble gases (or rare gases)

Question 13

Number of Periodic Table Group for Halogens

Answer 13

7A

Question 14

Number of Periodic Table Group for Alkaline earth metals

Answer 14

2A

Question 15

Number of Periodic Table Group for Chalcogens

Answer 15

6A

Question 16

Number of Periodic Table Group for Noble gases

Answer 16

8A

Question 17

Number of Periodic Table Group for Alkali metals

Answer 17

1A

Question 18

Properties of metals

Answer 18

Luster, high electrical and heat conductivity, solids at room temperature (except mercury)

Question 19

Properties of nonmetals

Answer 19

At room temperature, some are solids, some are gases, and one is liquid. Differ from metals in appearance and other properties.

Question 20

Properties of metalloids

Answer 20

Have properties that fall between metals and nonmetals (fall along line in Per. Tbl between metals and nonmetals

Question 21

Elements that exist as diatomic molecules

Answer 21

N2 (5A), O2 (6A), F2 (7A), Cl2 (7A), Br2 (7A), I2 (7A)

Question 22

define cation

Answer 22

an atom that has lost one or more electrons and is therefore positively charged

Question 23

define anion

Answer 23

an atom that has gained one or more electrons and is therefore positively charged