Chem test # 2 - grade 8

Question 1

What are particles made of?

Answer 1

molecules, ions, atoms

Question 2

How do you put electrons correctly into shells?

Answer 2

Fill from inner to outer. 2,8,8

Question 3

When is an atom stable?

Answer 3

When it has a full outer shell

Question 4

What are the noble gases?

Answer 4

They are the elements on the right side of the periodic table that have a full outer shell - meaning that they aren’t reactive

Question 5

What is an ion?

Answer 5

An ion is a positively charged atom. This is caused because it is missing or has gained electrons and there is a difference between the number of protons and electrons.

Question 6

How do you draw ions?

Answer 6

You draw the outer shell only and then you put brackets and a negative or positive number depending on if it has gained or lost electrons. Remember, use dot and cross diagram!!!

Question 7

Which gives what to who in ions?

Answer 7

You get two atoms with unstable outer shells and have the metal element give one or more electrons to a gaseous element.

Question 8

What is ionic bonding?

Answer 8

Ionic bonding is one or more electrons are transferred from one atom to another. the bonds are formed because now the elements are oppositely charged so there is attraction.

Question 9

What is an electrostatic force?

Answer 9

It is the attraction between a positive charge and a negative charge

Question 10

What does the structure of ionic compounds look like?

Answer 10

It is in a sort of cubic shape and it alternates the element and charge. Example:
Na+ Cl- Na+ Cl- Na+
Cl- Na+ Cl- Na+ Cl-

Question 11

Ionic compound is

Answer 11

Atoms joined together by ionic bonds. They have a high melting point and can conduct electricity when dissolved in water.

Question 12

Ionic bonds=
Metallic bonds=
Covalent bonds=

Answer 12

metal + non metal
metal + metal
non metal + non metal

Question 13

Covalent bonds

Answer 13

two non metal elements sharing one or more electron(s)

Question 14

How do you draw covalent bonds?

Answer 14

Only outer shell, draw the common electrons in the center of the two elements and both the lines overlap

Question 15

What keeps the bonds together?

Answer 15

In covalent bonding, they are kept together due to the shared electron(s) staying in the same region or ‘cloud of shared electrons’ between the two nuclei. Since the nucleons in the nuclei are positive, the negatively charged shared electron(s) and the nuclei are attracted to one another. (electrostatic force is created.

Question 16

Molecule?

Answer 16

A group of atoms held together by covalent bonds

Question 17

Differences between ionic and covalent compounds

Answer 17

Ionic: high melting and boiling points; strong attractive forces between ions; soluble in water but insoluble in organic solvents; conduct electricity when molten or dissolved in water.

Covalent: low melting and boiling points; inter molecular attractive forces are weak; insoluble in water (with exceptions); does not conduct electricity well.

Question 18

Why do ionic compounds carry electricity when in water?

Answer 18

Ionic compounds carry electricity because the water molecules are attracted to both the positive and negative ions. It is strong enough to pull them apart and they float around the water as individual ions. Because they become charged ions again, they also become charged carriers.

Question 19

What happens to glucose when dissolved in water?

Answer 19

The water molecules weaken the glucose molecules and essentially pull them apart. However, it doesn’t carry electricity well because they aren’t charged (neutral)

Question 20

Why do molten ionic compounds conduct electricity?

Answer 20

molten ionic compounds conduct electricity because the ions are mobile. Ions aren’t able to conduct electricity when in a solid shape.

Question 21

cation

Answer 21

positively charged ion

Question 22

anion

Answer 22

negatively charged ion

Question 23

Graph details

Answer 23

Use ruler
x axis = independent variable, y axis = dependent variable
use standard scale - points evenly apart
title must explain what graph will tell us. it can also be same title as chart
make points visible
line or curve of best fit does not connect all dots
put names + units on x and y axis

Question 24

Do you know what Brownian motion is?

Answer 24

Brownian motion is the random movement of particles suspended in a liquid or gas.

Question 25

In the symbol of an element from the periodic table, which number is the proton number? Which is the mass number?

Answer 25

The bigger number and top number is the mass number. The smaller and bottom number is the proton number.

Question 26

You should be able to draw the correct atomic structures for all of the atoms from hydrogen to calcium.

Answer 26

The proton number dictates the number of protons and electrons The Mass number - the proton number = the amount of neutrons Neutrons + protons are in the nucleus The electrons orbit the nucleus in energy levels or shells

Question 27

What is an atom?

Answer 27

smallest piece of an element - basic/fundamental unit of matter

Question 28

How can you tell the amount of electrons, neutrons, and protons?

Answer 28

The proton number dictates the amount of electrons The mass number - the proton number = the amount of neutrons

Question 29

what is Kinetic particle theory?

Answer 29

The kinetic particle theory states that matter is made up of particles and those particles are constantly in motion.