chemistry 10

Question 1

what is an isotope

Answer 1

each of two or more forms of the same element that contain equal numbers of protons but different numbers of neutrons in

Question 2

density

Answer 2

physical property

Question 3

what are all the signs of a chemical change

Answer 3

• odor
• gas / ubbles
• change in color
• change in temperature
• precipitate
• temperature change
• change in smell or taste

Question 4

what is a metalloid

Answer 4

an element whose properties are intermediate between those of metals and solid non - metals or semi conductors .

Question 5

what are exaamples of non metals

Answer 5

hydrogen , helium and neon

Question 6

what is the difference between a physical and chemical property

Answer 6

a physical property is a characteristic of a substance that can be observed or measured without changing the identity of the substance while a chemical property describes the ability to undergo a specific chemical change

Question 7

salt is dissolved into water

Answer 7

solution

Question 8

a solid element looks silvery and shiny when its surface has been freshly sanded and polished . It will stretch without breaking if enough pulling force is applied . This element is most likely classified as a

Answer 8

metal

Question 9

Salt ( NaCl ) is a

Answer 9

compound

Question 10

on the periodic table , elements in the same vertical column have the same

Answer 10

number of electrons in their outer shell

Question 11

what is a metalloid

Answer 11

has characteristics of both a metal and non metal

Question 12

the mass number of an atom is determined by the number of the number of

Answer 12

neutrons and protons

Question 13

an atom that loses 2 electrons

Answer 13

forms an ion wth a charge of +2

Question 14

ionic bonds might generally form between

Answer 14

alkali metals and halogens

Question 15

a covalent bond would most likely form between

Answer 15

phosphorus atom and a chlorine atom

Question 16

metals are good conductors of electricity because

Answer 16

ions conduct electricity

Question 17

explain why molecular compounds tend to have lower boiling points then ionic compounds

Answer 17

molecular compounds tend to have lower boiling points because ionic compounds . The bond is very strong and hard to break.

Question 18

If two objects of different temperatures are placed in contact, will heat naturally flow from the object with the higher thermal energy to the one with the lower thermal energy?

Answer 18

No, heat naturally flows from the object with a higher temperature to the one with a lower temperature. If 50 g of water at 30 o C is mixed with 250 g of water at 24 o C, heat will flow from the warmer water to the cooler water even though the thermal energy of the cooler water is much greater because there is so much more of it.

Question 19

Is it possible for heat to flow even if the thermal energies of two objects are the same?

Answer 19

Yes, heat flow depends on temperature difference not a difference in thermal energies. If a small piece of iron and a large piece of iron have the same thermal energy, the smaller one will be at a higher temperature and heat will flow into the cooler piece of iron.

Question 20

When boiling a pot of water, the handle of the pot gets hot.

Answer 20

This is an example of conduction – the molecules in the pot (a solid) are not free to move around over large distances. Heat is transferred as they collide with neighboring molecules.

Question 21

The Earth is constantly receiving energy from the sun. How does Earth maintain its relatively constant temperature?

Answer 21

Some of the energy from the sun is reflected so it does not raise the temperature of the Earth, but some of it is absorbed by the land, air, and water on the Earth. All objects emit radiation, even though it is not visible. The Earth emits infrared radiation, and the temperature balance is maintained by the Earth radiating as much energy into space as it absorbs from the sun.

Question 22

Compare the radiation emitted by the sun with the radiation emitted by the Earth. How are they similar and how are they different?

Answer 22

Radiation from the sun contains infrared, visible, and ultraviolet waves. Radiation from the Earth contains infrared waves only, and they are longer wavelengths than those that are received from the sun.

Question 23

Would you expect black asphalt or white sand to feel hotter on a sunny afternoon? Explain your answer.

Answer 23

Black asphalt would feel hotter because it absorbs more energy. The sand, because it is white, would reflect more energy.

Question 24

Which can hold more water vapour, warm air or cold air?

Answer 24

Warm air can hold more water vapour.

Question 25

What does it mean to say that the air is saturated?

Answer 25

If the air is saturated, it cannot hold any more water at its current temperature.

Question 26

What are condensation nuclei?

Answer 26

Condensation nuclei are particles that stimulate droplet formation. Water droplets will form around tiny particles such as dust and salt in the air.

Question 27

What does relative humidity mean?

Answer 27

Relative humidity is the percentage of water vapour in the air compared with the amount of water vapour that the air would contain if it was saturated.

Question 28

What is meant by the term “dew point”?

Answer 28

The dew point is the temperature at which the air is saturated and cannot hold any more moisture than it already has in it.

Question 29

What happens to the relative humidity when air is heated?

Answer 29

When air is heated, it can contain more moisture. Since the actual amount of water vapour is the same but the air could now hold more before it is saturated, the relative humidity will be lower.

Question 30

What happens when saturated air cools?

Answer 30

When saturated air cools, the water will condense out of the air because cool air cannot hold as much water as warm air. This condensation releases the latent h at of vaporization, so the air will not cool as fast as dry air.

Question 31

Where does the energy come from for the endothermic processes?

Answer 31

the sun

Question 32

Where does most evaporation occur – rivers, lakes, soil, or the ocean?

Answer 32

oceans

Question 33

What causes water vapor to condense into water droplets?

Answer 33

Movement of air into cooler regions, or the lowering of air temperature, causes water vapour to condense.

Question 34

Where would you expect there to be more precipitation, in an area near the ocean or an area more inland? Explain.

Answer 34

You would expect there to be more precipitation near the ocean since there would be more evaporation taking place there, and therefore more water vapour in the air.

Question 35

Explain why the temperature of dry land increases faster during the day and decreases faster during the night than the temperature of the water in lakes, rivers, and oceans.

Answer 35

Dry land changes its temperature faster than surrounding water because it has a smaller specific heat capacity. Also, convection is happening in the water so water is continually being exchanged between the surface and deeper. With the land, it is only the top layer that experiences changes in temperature.

Question 36

Explain what a sea breeze is. Include in your answer when and where it would occur and the process that causes it.

Answer 36

A sea breeze occurs near the shore during the day time. During the day, the land heats up more quickly than the nearby water. This heats up the air directly above the land, causing it to rise. As this air rises, cooler air from above the water moves in to replace it, resulting in a wind going from the water to the shore.

Question 37

covalent bonds are between

Answer 37

2 nonmetals

Question 38

ionic bond is between

Answer 38

between a metal and a nonmetal

Question 39

characteristics of ionic bonds

Answer 39

They form crystals.
They have high melting and high boiling points.
They are hard and brittle.

Question 40

characteristics of covalent bonds

Answer 40

The melting and boiling points of covalent compounds are generally low.
Covalent compound are insoluble in water but dissolve in organic solvents.
They are non-conductors of electricity in solid, molten or aqueous state.