Matter and its Changes

Atoms

• Matter is made up of atoms

• Matter is anything that takes up space and has mass

• Atoms are the “building blocks” of life

• Forms of matter that contain only one type of atom are called elements

• Atoms combine to form many different types of matter

Structure of an Atom

ProtonElectron (electron cloud)

Neutron

Mass Number =

Protons + Neutrons

Atomic Number =

Number of protons

Isotopes

• When the number of protons in an atom changes it becomes a different element

• Atom is electrically neutral when the number of electrons and protons are the same.

• Atoms of the same element that have a different number of neutrons are called isotopes

• Ex. C12 = 6p +6n C14 = 6p + 8n

Ions

• Electrically charged atoms are called Ions• The number of protons is not equal to the

number of electrons• Ions are attracted to each other when they have

opposite charges

• Ex. Na+ + Cl- = NaCl = salt• Ex. Na+ + F- = Sodium Fluoride for

toothpaste

Combinations of Atoms

• Atoms combine by sharing their outermost electrons in their electron clouds

• When two atoms are combined a molecule is formed

Bonds

• Ionic Bond – Positive and Negative ions combine and electrons are transferred– Ex. NaCl

• Covalent Bond – Electrons are shared– Ex. H2O

Combinations of Atoms

How Atoms Combine

• When at least two atoms are combined a molecule is formed

• There are two ways in which atoms combine to form molecules and compounds

Ionic Bonding

• Positive and Negative ions combine and electrons are transferred

• Example: Na+ and Cl- = NaCl

Covalent Bonding

• In covalent bonding electrons are shared

• Example: 2H + O = H2O

Compound

A type of matter that has properties different from the properties of each of the elements in it

• Example: Na (metal) + Cl (gas) = NaCl (solid salt)

• Example: 2H (gas) + O (gas) = H2O (liquid water)

Mixture

• Many different substances that when mixed together, each substance retains its own properties

• Examples: sand, air and salad

Solution

• When one substance of a mixture is dissolved in another substance it is a solution

• Examples: tea w/ sugar, salt water

• Chemical properties describe how one substance changes when it reacts with another

• Examples: iron and oxygen = rust

• Physical Properties can be observed or measured without changing the substance

• Examples: color, shape, size, density and texture

If energy is added or taken away, matter changes phases

Matter can change by:Matter can change by:

1.1. Increasing or decreasing the Increasing or decreasing the temperaturetemperature

Ex: freezing water turns it to a solid Ex: freezing water turns it to a solid (ice)(ice)

2. Increasing or decreasing pressure2. Increasing or decreasing pressure

Ex: Pressure to ice cube changes it to Ex: Pressure to ice cube changes it to liquidliquid

4. Liquid to a solid: 4. Liquid to a solid: freezing pointfreezing point

5. Liquid to gas: 5. Liquid to gas: evaporation pointevaporation point

6. Only substance that occurs naturally 6. Only substance that occurs naturally as a solid, liquid, and gas: as a solid, liquid, and gas: WaterWater

Changes of State

freezing

Increasing Energy Gases

Liquids

Solids

boiling condensing

melting

Sublimes deposition

Let us consider how the particles are arranged in the 3 states of matter. (phases)

Particles have slightly more energy so are able tomove randomly around each other and are spaced slightly further than in a solid. However they do not have sufficient energy to overcome the attractive forces between them so cannot escape from each other completely.

Particles arranged in a regular, close-packed fashion. They have little energy, so simply vibrate about fixed positions, unable to overcome the attractive forces between them.

LiquidSolid Gas

Particles have much more energy so have overcome all attractive forces between them. They move around very fast in a irratic fashion, colliding occasionally. They are much more spread out then in the solid or liquid state

Plasma

• Plasma is like a gas, but the atoms are made up of free electrons and ions.

• Plasmas are not common on Earth, however you may have seen plasma.– Northern lights or lightning

State Changes or Phase Change

• When a substance changes state, it is undergoing a physical change, there is no new substance formed. Physical changes unlike chemical changes are easy to reverse.

• Energy is required to turn from solids to liquids, and liquids to gases. In order to gain greater freedom of movement, the forces between the particles must be overcome.

• Energy is given up as gases turn to liquids, and liquids to solids. They move less freely and are held together more strongly.

DensityDensity

What is What is densitydensity??

The measure of the mass of an The measure of the mass of an object divided by its volume.object divided by its volume.

Energy from AtomsEnergy from Atoms

1.1. What is What is nuclear energynuclear energy??- Alternate energy source produced Alternate energy source produced

from atomic reactionsfrom atomic reactions

2. How 2. How fissionfission produces nuclear produces nuclear energy:energy:

- Splitting the nucleus of atoms in - Splitting the nucleus of atoms in heavy elementsheavy elements

3. Most commonly used fuel in nuclear 3. Most commonly used fuel in nuclear power plants: power plants:

- - Uranium 235Uranium 235

Where is it found? Where is it found?

- - Sandstones in the Rocky MountainsSandstones in the Rocky Mountains

4. Major source of nuclear waste: 4. Major source of nuclear waste: - - Radioactive materialRadioactive material

Most common method of storing Most common method of storing nuclear waste: nuclear waste:

- Power plantsPower plants

Can remain active for Can remain active for 10,000 years10,000 years

Two advantages to storing nuclear Two advantages to storing nuclear waste at Yucca Mountain:waste at Yucca Mountain:

1.1. Remote area (deserted)Remote area (deserted)

2.2. Water table is far below storage Water table is far below storage facilityfacility

Two disadvantages to storing Two disadvantages to storing nuclear waste at Yucca Mountain:nuclear waste at Yucca Mountain:

1.1. Earthquakes could destroy storage Earthquakes could destroy storage facilityfacility

2.2. Large amount of nuclear waste in Large amount of nuclear waste in one areaone area