Unit 2: Matter -- Atoms, Molecules, and Ions

Question 1

matter

Answer 1

whatever occupies space and can be perceived by our senses.

Question 2

mass

Answer 2

quantity of matter (always conserved).

Question 3

Law of Conservation of Mass

Answer 3

no mass is lost from the start of a process to the end; the sum of the masses of the reactants in a chemical equation is equal to the sum of the masses of the products (ex: Zn + S = ZnS).

Question 4

extensive property

Answer 4

dependent on the amount of substance (ex: mass, volume).

Question 5

intensive property

Answer 5

independent on the amount of substance (ex: color, melting/boiling point, density, temperature, solubility, malleability, luster).

Question 6

physical property

Answer 6

can be observed without performing a chemical reaction (ex: luster, hardness, color).

Question 7

chemical property

Answer 7

cannot be observed without performing a chemical reaction (ex: flammability, reactivity).

Question 8

element

Answer 8

pure substance that cannot be separated by physical or chemical means (this includes diatomic and polyatomic molecules with only one element).

Question 9

compound

Answer 9

pure substance composed of two or more different elements bonded together in fixed proportions. Can be broken down into individual elements via chemical means.

Question 10

homogenous mixture

Answer 10

components are distributed uniformly through the sample and have no visible boundaries or regions (ex: sugar in coffee).

Question 11

heterogenous mixture

Answer 11

components are not distributed uniformly and there may be distinct regions with different compositions (ex: sand in water, chocolate chip cookie).

Question 12

distillation

Answer 12

separating substances from a liquid mixture by using selective boiling and condensation.

Question 13

filtration

Answer 13

separating solid matter and liquid matter from a mixture using a filter.

Question 14

Law of Multiple Proportions

Answer 14

mass cannot be created or destroyed; when two elements react to form more than one compound, a fixed mass of one element will react with masses of the other element in a ratio of small, whole numbers.

Question 15

atomic theory

Answer 15

1. Matter is composed of atoms (the smallest particle capable of participating in chemical reactions)
2. Elements contain only one type of atom characteristic of that particular element
3. Atoms of one element have different properties from another element
4. Law of Definite Proportions
5. Atoms are neither created nor destroyed during a chemical reaction, but rearranged

Question 16

gold foil experiment

Answer 16

alpha particles used to bombard gold foil; mass was discovered to be at the center of the atom, therefore it contains the majority of the atom’s mass.

Question 17

metals

Answer 17

shiny solids; conduct heat and electricity; are malleable.

Question 18

nonmetals

Answer 18

solids, liquids, and gases; nonconductors; solids are brittle.

Question 19

metalloids

Answer 19

shiny solids; semiconductors; brittle.

Question 20

isotopes

Answer 20

atoms of the same element that contain a different number of neutrons, and thus have a different atomic mass.

Question 21

average atomic mass

Answer 21

weighted average of all the masses of all isotopes of an element; calculated by multiplying natural abundance (proportion of a particular isotope [%]) of each isotope by the mass [amu] of each isotope and summing the products.

Question 22

ions

Answer 22

neutral atoms that gained/lost electrons, held together by electrostatic force (opposites attract).

Question 23

cations

Answer 23

positive ions

Question 24

anions

Answer 24

negative ions

Question 25

ionic compounds

Answer 25

made of a metal (form cations) and nonmetal (form anions). Charges depend on location in the periodic table.

Question 26

Law of Definite Proportions

Answer 26

all samples of a pure compound contain the same elements in the same proportion by mass.