Chapter 7 Test Study Guide

Question 1

What is an atom and an element?

Answer 1

.

Question 2

What is a compound?

Answer 2

Two or more elements chemically combined.

Question 3

What was Dalton’s model of the atom?

Answer 3

1. all matter is made up of atoms
2. atoms of each element are the same.
3. different elements have different masses.
4. atoms of different elements can join to form compounds.

early 1800s; based on experiments with gases; hydrogen and oxygen-water; atoms like a solid sphere.

Question 4

What is an electron, who identified, and where in an atom is it found?

Answer 4

an electron is a subatomic particle that has negative charge and is located outside of the atom’s nucleus. Joseph Thompson discovered in in the late 1800s.

Question 5

What is a proton and where in the atom can it be found?

Answer 5

A proton is a subatomic particle located in the nucleus of the atom and has a positive charge.

Question 6

What is the nucleus of an atom, who identified it, and what does it contain?

Answer 6

Discovered by Rutherford, the nucleus contains protons and neutrons, and the nucleus is the central region of the atom.

Question 7

What are energy levels and who first described them?

Answer 7

Energy levels move electrons around the atom. Niels Bohr was the first to describe them.

Question 8

Name and describe the current model of an atom.

Answer 8

The “Electron Cloud Modes” 1. electrons don’t orbit around the nucleus. 2. electrons travel in an energy level but in ever-changing paths.

Question 9

What is a neutron and where is it found in the atom?

Answer 9

A subatomic particle with no electric charge located in the nucleus.

Question 10

What is the atomic number of an atom?

Answer 10

Is the number of protons and electrons an atom has. It is used to identify elements.

Question 11

How is the atomic number related to the number of electrons in an atom?

Answer 11

The atomic number tells you how many protons are in an atom. Protons are positive and an atom needs to be neutral; so if there are 5 protons there has to be 5 neutrons.

Question 12

What is the atomic mass of an atom?

Answer 12

number of protons and neutrons an atom has. (used to identify isotopes)

Question 13

How many protons, neutrons and electrons are in this atom?

Answer 13

.

Question 14

What is an isotope

Answer 14

an isotope is atoms of the same element that have different numbers of neutrons and therefore different atomic masses.

Question 15

What is different between H-3 and H-2

Answer 15

They have a different atomic mass. It is an isotope.

Question 16

What is a diatomic compound?

Answer 16

DC-gases that occur in nature always as a pair (never alone) ex: oxygen o2, hydrogen H2 and iodine Ix (etc)

Question 17

What is a “BrINCIHOF” gas?

Answer 17

The 7 gases that are diatomic compounds. Bromine, Iodine, Nitrogen, Chlorine, Hydrogen, Oxygen, and Florine.

Question 18

What is the relative abundance of solid, liquid and gaseous elements?

Answer 18

Most are solids, followed by gases, followed by liquids.

Question 19

What is a chemical symbol?

Answer 19

Chemical symbols represent an element. 1 or 2 letters (First letter is capitalized)

Question 20

What are some examples of elements and their chemical symbols?

Answer 20

Hydrogen: H
Helium: He
Nitrogen: N
Uranium: Ur

Question 21

How do the properties of a compound relate to the properties of the elements used to create it?

Answer 21

• elements combined=to make a compound.
• most are solids at room temperature.
• metal can conduct electricity.
• 2 liquids at room temperature.

Question 22

What does it mean that compound have definite chemical composition?

Answer 22

the ratio of elements is always the same.

Question 23

What is molecular compound?

Answer 23

• 2 or more elements help together sharing electrons.
• sharing electrons is a covalent bond.
• most liquids and gases are molecular compounds.

Question 24

What is a covalent bond?

Answer 24

shared electrons. O–> O- =O=O ex: Hydrogen H2

Question 25

What are some examples of molecular compounds?

Answer 25

Liquids –> H20 + Gases –> CO2

Question 26

What is an ion?

Answer 26

.

Question 27

How do you generate a cation (+)??

Answer 27

loose an electron.

Question 28

How do you generate an anion (-)?

Answer 28

gain an electron

Question 29

How do you form an ionic bond?

Answer 29

when an atom takes an electron from another
O- –> O
+ or O2 -

Question 30

What are some examples of compounds held together by ionic bonds?

Answer 30

Na+ + Cl –> NaCl

Question 31

What role does neutrality play in forming an ionic compound?

Answer 31

2 or more ions were together to form a compound with no charge.

Question 32

What is chemical formula

Answer 32

(check definition)

combination of symbols and numbers that represent the composition of a compound. ex: 3H2O

Question 33

What does the coefficient represent in a chemical formula?

Answer 33

number of molecules of compound/little number.

Question 34

What does the subscript represent in a chemical formula?

Answer 34

number of atoms of each element. little number x by big number.

Question 35

How many atoms of each element in 6 CCl4? 2NH3 and Na2Cl3?

Answer 35

6 CClu–6Cl24Cl
Na2Cl3
2nal3CL
2NH3- 2nl6H

Question 36

What is a homogeneous mixture?

Answer 36

all parts contain same amount of each element. (most are liquids-ex: milk)

Question 37

What is a heterogeneous mixture?

Answer 37

not every part has the same composition/ex dirt or sand.

Question 38

What are the main differences between a mixture and a compound?

Answer 38

mixture:
physically combined
can be easily undone
properly based composition

compound:
chemical bonds formed
hard to reverse
new or different properties than components.