Chapter 2.3

Question 1

Density

Answer 1

the mass of an object divided by its volume.

Question 2

States of Matter

Answer 2

1) Solids have a definite shape and volume
2) Liquids take the shape of their container
3) Gases spread out and fill their containers
4) Plasma occurs at high temperatures and has such high energy that some electrons may escape their electron clouds

Question 3

What can cause changes in the state of matter?

Answer 3

Both:

1) Temperature and
2) Pressure

Question 4

What can change and what can NOT change when matter changes state?

Answer 4

–> Physical properties can change but

–> Chemical properties do NOT CHANGE when matter changes state.

Question 5

Plasma occurs at

Answer 5

HIGH TEMPERATURES and has such HIGH ENERGY that some electrons may escape their electron clouds

Question 6

Solids will melt at lower temperatures when pressure is ____________

Answer 6

increased

Question 7

Decreasing pressure lowers the _________ ___________ of liquids

Answer 7

boiling points

Question 8

Decreasing pressure ________ the boiling points of ________

Answer 8

lowers liquids

Question 9

Matter

Answer 9

anything that has mass and takes up space.

Question 10

Atom

Answer 10

the smallest particle of an element that still retains the properties of the element.

Question 11

Element

Answer 11

substance that is made of only one type of atom.

Question 12

Proton

Answer 12

particle inside the nucleus of an atom that has a charge of 1+.

Question 13

Neutron

Answer 13

particle without an electrical charge.

Question 14

Electron

Answer 14

particle with a negative charge.

Question 15

Atomic Number

Answer 15

number of protons in an atom’s nucleus.

Question 16

Mass number

Answer 16

the number of protons plus the number of neutrons in an atom.

Question 17

Isotope

Answer 17

atoms of the same element that have different numbers of neutrons.

Question 18

Compound

Answer 18

atoms of more than one type of element that are chemically bonded together.

Question 19

Molecule

Answer 19

a group of atoms connected by covalent bonds.

Question 20

Ion

Answer 20

electrically-charged atom whose charge results from an atom losing or gaining electrons.

Question 21

Mixture

Answer 21

a combination of substances in which the individual substances do not change or combine chemically but instead retain their own individual properties; can be gases, solids, liquids, or any combination of them.

Question 22

Heterogeneous mixture

Answer 22

a mixture which is not mixed evenly and each component retains its own properties.

Question 23

Homogeneous mixture

Answer 23

solid, liquid, or gas that contains two or more substances blended evenly throughout.

Question 24

Solution

Answer 24

a mixture which is evenly mixed throughout; also known as a homogeneous mixture.

Question 25

Density

Answer 25

measurement of the mass of an object divided by its volume.

Question 26

John Dalton theory of atoms:

Answer 26

1. Every element is made of tiny, unique particles called atoms that CANNOT be subdivided. 2. Atoms of the same element are exactly alike. 3. Atoms of different elements can join to form molecules.

Question 27

Niels Bohr suggested that electrons:

Answer 27

electrons move in set paths like planets that surround the sun.

Question 28

There are energy levels in which ___________ must move through. When an electron gains energy, it moves to a _________ \_\_\_\_\_\_\_\_\_ level. When it loses energy, it moves to a ________ \_\_\_\_\_\_\_\_\_\_ level.

Answer 28

There are energy levels in which **_electrons**_ must move through. When an electron gains energy, it moves to a _**higher energy**_ level. When it loses energy, it moves to a _**lower energy_** level.

Question 29

There are energy levels in which e\_\_\_\_\_\_\_ must move through. When an electron gains energy, it m\_\_\_\_\_ to a h\_\_\_\_\_\_ e\_\_\_\_\_\_ l\_\_\_\_\_. When it loses energy, it moves to a l\_\_\_\_\_\_\_ e\_\_\_\_\_\_\_ l\_\_\_\_\_\_.

Answer 29

There are energy levels in which **_electrons_** must move through. When an electron gains energy, it **_moves_** to a **_higher energy level**_. When it loses energy, it moves to a _**lower energy level_**.

Question 30

In the modern atomic model, electrons are found

Answer 30

in orbitals (s, p, d, f…) within each energy level.

Question 31

The electrons in the outermost energy level are called:

Answer 31

**_ valence electrons._**