Matter and Energy

Sections 1.3 and 1.4 Science 7Mr. Nigh

Matter Combines to form different substances

Most of the substances in the world are mixed

Matter can be pure or it can be two or more substances mixed together

Drinking water may appear to be pure, but may have many minerals dissolved in it.

Often the difference between pure and mixed may only be visible on the atomic or molecular level

ElementsAn element is a substance that

contains only a single type of atom

The number of atoms is not important

An element cannot be separated into other substances

Gold Silver

CompoundsCompounds are substances that

consist of two or more different types of atoms bonded together

Some types are made of molecules such as water and carbon dioxide

Others are made of elements bonded together like salt

Salt

Salt is a compound that has very different properties then the elements that make it up

Sodium and Chlorine are poisonous by themselves

But when combined, they create a compound (table salt) that is safe to eat

MixturesA mixture is a combination of

different substances that remain the same individual substances and can be separated by physical means

For example: a fruit salad is not a different kind of fruit, the parts can be separated by physical means

Fresh Fruit Salad

Parts of mixtures can be the same or different throughout

SoilSeveral handfuls of soil may have

different properties in different parts of your backyard

The soil in the yard is thus an example of a heterogeneous mixture, different properties in different parts of the mixture

Soil Layers

Kool-aidYou know the color and flavoring in

Kool-aid are there because you can see and taste them

One drop of the liquid is essentially the same as another drop

Thus this is an example of a homogeneous mixture

Comparing mixtures and compounds

Substances in mixtures remain the same, in compounds new substances are formed by atoms that bond together

Mixtures can be separated by physical means, compounds only by breaking bonds

Proportions in mixtures vary, compounds are fixed because the type and number of atoms are always the same

States of MatterThe four familiar states of matter

are solid, liquid, gas and plasmaWhen a substance changes from

one state to another, the molecules in the substance do not change

However the arrangement of molecules does change giving each state of matter its own characteristics

SolidIt has a fixed volume and a

fixed shapeParticles are close together

and form a regular patternParticles cannot move from

one location to another, fixed

LiquidLiquid has a fixed volume, but

no fixed shapeUsually the shape of the

container it is inParticles are attracted and

close, but are not fixed and may move from one place to another

GasA gas has no fixed volume or

shapeParticles are not close together

and may move from one place to another

Space between particles can increase or decrease with pressure

Gas Behavior• Gas molecules are always in

motion, continually hitting each other and applying pressure to the sides of any container they are in

• As in a bicycle tire, the more molecules are put in, the harder the outside of the tire becomes

• The speed at which gas molecules move depends on the temperature, higher temperature molecules move faster

PlasmaPlasma

Although it is the least familiar state of matter to us here on Earth, plasma is actually the most common form of matter – 99% of all visible matter in the Universe.

In a plasma, a significant number of electrons have such high energy levels that no nucleus can hold them.

Earth Plasma examples

Plasma in the universe

Orion NebulaHorsehead nebulaHorsehead nebula

Egg NebulaEgg Nebula

Plasma on the Sun

Volume, temperature, and the pressure of gasses have a

unique relationship--Difficult Concept-- Listen

IncreaseDecrease

Stay the same

If the temperature of the gas stays the same, increasing the pressure of the gas decreases its volume

If the volume stays the same, increasing the temperature increases the pressure

If the pressure of the gas stays the same, increasing the temperature of the gas also increases the volume

Which two characteristics determine the state of matter?

The arrangement and the motion of particles

Which state of matter has particles that are farthest

apart?

Gas

Which state of matter has particles that are generally

close together?

Solid

Which state of matter has particles that can slide past each other but cannot move

freely in any direction

liquid

What happens to the volume of a gas if the temperature stays the same and the pressure on the

gas increases?

Itdecreases

What happens to the pressure of a gas if the volume stays the

same and the temperature increases?

Itincreases

What happens to the volume of a gas if the pressure stays the same and the temperature

increases?

It increases

The

End