Chemistry Vocabulary

Question 1

Valance Electrons

Answer 1

Electrons found in the outermost orbit of an atom (found in valence shell).

Question 2

When is an atom neutral?

Answer 2

When the number of electrons is equal to the number of protons.

Question 3

When is an atom charged?

Answer 3

When the number of electrons is not equal to the number of protons.

Question 4

Ion

Answer 4

An ion is a charged atom, formed when electrons are either gained or lost. Valence electrons are always the first to be lost.

Question 5

Hardness

Answer 5

A measure of the resistance of a solid to being scratched. Ex. a diamond is hard, chalk is soft.

Question 6

State

Answer 6

At room temperature the state at which the substance occurs (either solid, liquid, or gas) Ex. water-liquid, gold-solid, helium-gas.

Question 7

Malleability

Answer 7

A measure of how easily the substance can be bent or hammered into a certain. Applies to solid metals. Ex. malleable- gold (at 24k), not malleable-steel.

Question 8

Ductility

Answer 8

A measure of how easily a metal can be pulled to form wires. Ex. ductile-copper, aluminum, not ductile- calcium, lithium.

Question 9

Crystal Form

Answer 9

If a substance is made of crystals, then it will have a unique crystal pattern or form. Ex. snow, sugar, salt, carbon.

Question 10

Solubility

Answer 10

A measure of how easily a substance dissolves in water. Ex. Sugar, salt, vinegar, dissolve in water, oil does not.

Question 11

Viscosity

Answer 11

A measure of thick a liquid is when pouring it. Ex. High viscosity- ketchup, maple syrup, molasses, low viscosity- water, olive oil, vinegar.

Question 12

Combustibility

Answer 12

A measure of how easily a substance catches on fire or explodes. Ex. Hydrogen is combustible, helium is not.

Question 13

Reaction with acid

Answer 13

Whether a substance reacts with acid how it reacts if it does. Ex. baking soda, reacts with acid and forms carbon dioxide and water.

Question 14

Physical Property

Answer 14

A physical property is an aspect of a substance that does not involve forming any new substances. They can be experienced through senses.

Question 15

What is something each substance has that is unique?

Answer 15

Each substance has a unique melting point and boiling point.

Question 16

What can be used to identify a mystery substance?

Answer 16

Melting, boiling point and density.

Question 17

What can affect melting and boiling points?

Answer 17

The purity of a substance can affect the melting and boiling points.

Question 18

State the temperatures water melts/freezes and boils at?

Answer 18

Water melts/freezes at 0 degrees celsius and boils at 100 degrees celsius.

Question 19

Density

Answer 19

A measure of how much matter (mass) is present per unit of volume. It indicates how tightly the particles are packed.

Question 20

Give an example of density.

Answer 20

The density of water is 1g/mL. Ice floats so it is less dense than that, metals sink so they are more dense.

Question 21

Physical Change

Answer 21

A physical change is a change that does not create any new substances. They may include changes of state. They are reversible.

Question 22

Chemical Change

Answer 22

A chemical change is a change in a substance that produces new substances. These are reversible. (If the product of the starting substances is different then there has been a chemical change.)

Question 23

Chemical Property

Answer 23

How a substance predictably behaves around other substances. Some are very reactive, some are not. Some react under only certain conditions.

Question 24

What is special about how the periodic table is organized?

Answer 24

The periodic table is organized in such a way that reactions can be predicted based on the chemical properties of elements.

Question 25

Oxidation number

Answer 25

The oxidation number of an element tells you how far an element is away from a full valence shell. It can be positive or negative. Ex. Aluminum has an oxidation of 3+.

Question 26

Polyatomic ion

Answer 26

An ion that has a stable group of several atoms acting together as a charge particle.

Question 27

How is charge shared throughout a polyatomic ion?

Answer 27

The charge in this type of ion is shared over the whole ion, unlike just one atom.

Question 28

What is an example of a polyatomic ion? Describe it?

Answer 28

Sodium Phosphate, is a white solid, quite stable and an electrolyte. The chemical formula for sodium phosphate is: Na3PO4

Question 29

Molecular Compounds

Answer 29

Molecular compounds are pure substances formed from two or more non-metals.