Chem test # 1 - grade 8

Question 1

All matter is made up of

Answer 1

particles

Question 2

Particles include:

Answer 2

Molecules, ions, atoms

Question 3

Atoms:

Answer 3

smallest piece of element - basic/fundamental unit of matter

Question 4

Molecules:

Answer 4

One or more atoms connected by chemical bonds

Question 5

Ions:

Answer 5

atom or molecule that has a positive or negative charge

Question 6

What is random particle motion?

Answer 6

Particles are always in motion
Random particle motion is brownian motion
Brownian motion is caused by the smaller (invisible) particles colliding with the bigger particles, causing them to move randomly.

Question 7

Do you know what Brownian motion is?

Answer 7

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

Question 8

In Brownian motion, lighter/smaller particles move faster than heavier/larger ones. Why?

Answer 8

Smaller/lighter particles move faster than heavier particles because their mass is less. So when they collide with the invisible particles, they move faster because the same amount of force on the smaller particle moves it a lot more than larger particles.

Question 9

How are particles arranged in gases?

Answer 9

Particles move rapidly
Particles collide with one another + container wall. Take the shape of the container
Particles are very distant from one another
Gas particles have a weak force of attraction
no volume

Question 10

How are particles arranged in liquids?

Answer 10

Particles are close together
Particles ‘flow’ together and take the shape of their container
They have a medium force of attraction
arrangement: random - no fixed pattern
defnite volume

Question 11

How are particles arranged in solids?

Answer 11

Particles are very close together
Particles ‘vibrate’ together
They have a high force of attraction
Arrangement - fixed pattern
definite volume and definite shape

Question 12

Can you explain why gasses exert pressure on the inner walls of containers?

Answer 12

When gasses are confined in a container, their fast moving characteristic and their low force of attraction makes them collide with the walls of the container, therefore exerting pressure

Question 13

Higher temperature =

Answer 13

Higher kinetic energy

Question 14

What are the parts of an atom?

Answer 14

Nucleus (protons and neutrons) in the center with electrons orbiting outside it.
Electrons orbit the nucleus in rings called energy levels/shells.

Question 15

What are the charges and masses of subatomic particles in an atom?

Answer 15

Protons: Positive charge (+1) Mass: 1amu
Neutrons: Neutral charge (0) Mass: 1amu
Electrons: Negative charge (-1) Mass: 1/1800amu
When you count the mass of an atom, you exclude the electrons since they barely make a difference

Question 16

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

Answer 16

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

Question 17

Can you place the electrons of an atom correctly into “shells”?

Answer 17

2 in the first shell, then 8 in the second and third shells. Always add electrons from the inner to outer shells.

Question 18

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

Answer 18

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 19

The shorthand way to express the electronic structure…

Answer 19

The shorthand way to express the electronic structure gives the number of electrons in each shell. For example: Mg 2, 8, 2. Since there are 2 electrons in the first shell, 8 electrons in the second, and 2 in the third.

Question 20

What are isotopes?

Answer 20

Isotopes are the same element but with a different amount of neutrons. The chemical properties are the same although sometimes they can be radioactive

Question 21

Are isotopes radioactive?

Answer 21

Some isotopes are radioactive but not all. An isotope is radioactive because the nucleus decays, emiting rays or particles that can be harmful. The radioactive isotopes are called radioscopes.

Question 22

The number of protons determines…

Answer 22

what the element is and what chemical properties the element has

Question 23

Can you explain why Brownian motion occurs?

Answer 23

Brownian motion is caused by smaller, invisible, particles colliding with bigger, visible, particles causing them to move randomly. When there is more force on one side of the particle it will move in that direction.

Question 24

What is the relationship between pressure and temp?

Answer 24

As the temp increases, the particles move faster and hit the walls of the container with increased force and frequency. This is kinetic energy. Since the particles are exerting more force more frequently on the walls of the container it increases the perssure as well.

Question 25

What happends when the temperature increases in a gas?

Answer 25

When the temperature increases, the gas particles move faster and there is an increase of kinetic energy due to the particles hitting the walls of the container with increasing force and speed.

Question 26

What happeneds when the pressure increases in a gas?

Answer 26

When the pressure increases, the gas molecules get closer together and hit the walls of the contaner more often

Question 27

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

Answer 27

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

Question 28

what is Kinetic particle theory?

Answer 28

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

Question 29

What would cause pressure to increase in a gas?

Answer 29

If we decrease the volume of a gas, the molecules get closer tofether and hit the wall of the container more often, therefore increasing pressure