By Aimee Chavez. Matter Heterogeneou s mixture Homogenous Mixture solutionPure substance compoundElement Uniform Distribution? YES NO Fixed Composition.

MATTER By Aimee Chavez

Matter

Heterogeneous mixture

Homogenous Mixture

solutionPure substance

compoundElement

Uniform Distribution?

YESNO

Fixed Composition ?

Yes No

Can it be broken down into simpler

substances?

Pure Substances

Matter that has exactly the same composition. Has a fixed, uniform composition.

Can be an element or a compound.

Elements A substance that cannot be broken down

into simple substances. An atom is the smallest particle of an element. An element has a fixed composition because it contains only one type of atom.

Examples are nitrogen and oxygen the two main gases you breathe.

Compounds

Made from two or more simpler substances.

Can be broken down to simpler substances.

Properties differ from those substances that make them. Example o and H are gases at room temperature, but water is a liquid.

Contains 2 or more elements joined in a fixed proportion. H₂O CO₂ Na Cl

Mixtures Retain some of the properties of their

individual substances. Properties of a mixture can vary because

the composition of a mixture is not fixed. The type of pepper and quantity used determines hotness.

May or may not be evenly distributed : homogenous and heterogeneous

Heterogeneous Means different and kind Particles are noticeably different from one

another.

Homogenous

The substances are so evenly distributed that it is difficult to distinguish one substance in the mixture from another.

Based on the size of its largest particles, a mixture can be classified as a solution, a suspension, or a colloid.

Solutions

When substances dissolve and for a homogenous mixture, the mixture that forms is called a solution.

The particles are too small to settle out of the solution, be trapped by a filter, or scatter light.

Suspension

A heterogeneous mixture that separates into layers over time.

Particles will settle out or can be trapped by a filter because they are larger than the particle in a solution.

Can scatter light.

Colloids

Contains some particle that are intermediate in size between the small particles in solution and the larger particles in a suspension.

Don’t separate into layers and cant use filter paper to separate particles.

Can scatter light. Examples: milk, fog (water droplets in air)

Physical Properties

Viscosity Conductivity Malleability Hardness Melting point Boiling point Density Ductility Magnetism

Viscosity: the tendency of a liquid to keep flowing – its resistance to flowing .

Greater = slower the liquid moves Viscosity usually decreases when heated

Conductivity

Ability to allow heat to flow. Those materials that have a high

conductivity like metals are called good conductors.

Usually means conductors of heat and electricity.

Malleability

Ability of a solid to be hammered without shattering.

Most metals are malleable.

Hardness

One way to compare is to see which material scratches the other.

Diamond is the hardest mineral and Talc is softest.

Melting and Boiling Point The temperature at which a substance changes from solid

to liquid is its melting point. Water = 0° C

The temperature at which a substance boils is its boiling point.

Water = 100 ° C

Density

Physical Changes Some of the properties of the material

change, but the substances in the material remain the same.

Water from liquid to a gas during boiling Crumpling and slicing change sixe and

shape. Some can be reversed (freezing and

melting)

Chemical Properties

Any ability to produce a change in composition of matter.

Can be observed only when the substances in a sample of matter are changing into different

substances.

Flammability

Materials ability to burn in the presence of oxygen.

Sometimes not desirable property. Children's sleepwear. (flame-resistant)

Materials that can burn are used for fuel.

Reactivity

How readily a substance combines chemically with other substances.

Oxygen is reactive easily with most other elements. Rust

Nitrogen is not reactive and used on ships as a gas to decrease rusting.

Recognizing chemical changes

1. color: clue that new substance is formed. A bracelet turning darker. (tarnish)

2. production of gas: bubbles (vinegar and baking soda) , expanding & rising (baking powder), hissing.

3. formation of precipitate: curdling of milk, any solid that forms and separates from a liquid mixture.

States of Matter

Matter can be classified as solids, liquids, or gases based on whether their shapes and volumes are definite of variable.

Kinetic theory of matter: all the particles of matter are in constant motion.

solidsHas a definite shape and definite volume. Particles only slightly vibrate and are packed close together. Crystalline: particles are arranged in repeating 3D pattern called a crystal. Amorphous: particles are in a random arrangement.

Liquids

Takes the shape of its container and has a definite volume. Molecules slide past each other.

Buoyant Force The upward force on and object

immersed in a fluid. If the buoyant force is equal to the object

then it floats. If the buoyant force is less than the

object then it sinks.

Pascal’s Principle When a force is applied to a confined

fluid any increase in pressure is transmitted equally to all parts of the fluid.

The human heart has two force pumps.

Gases

No definite shape of volume. Takes shape and volume of container.

Molecules move freely past each other.

Gas Pressure

Pressure: unit is Pascal (Pa) Collisions between particles of a gas and

the walls of the container cause the pressure in a closed container of gas.

The more frequent the collisions, the greater the pressure of the gas is. The speed of the particle and their mass also affect the pressure.

Factors that affect Gas Pressure

1. Temperature: raising the temperature of a gas will increase its pressure if volume of the gas and the number of particles are constant.

2. volume: reducing the volume of a gas increases its pressure if the temperature of the gas and number of particles are constant.

3. number of particles: increasing the number of particles will increase the pressure of a gas if the temperature and the volume are constant.

plasma

Extremely high temperatures , such as those found on the sun or other stars, matter exists as plasma.

Phase Changes The reversible physical change that

occurs when a substance changes from one state of matter to another.

Melting Freezing Vaporization Condensation Sublimation deposition

Energy and Phase Changes

Energy is either absorbed or released during a phase change.

Endothermic: the system absorbs energy from its surrounding. Melting

Exothermic: the system releases energy to its surroundings. Freezing

Melting: at the m.p. of water 0°C some molecules gain enough energy to overcome their attraction and move from their fixed position . When all molecules have enough energy to move melting in complete.

Freezing: at f.p. of water some molecules move slowly enough for the attraction between molecules to have an effect. When all molecules are drawn into an orderly arrangement freezing is complete.

Vaporization: when a substance changes from a liquid into a gas. (endothermic)

Evaporation: the process that changes a substance form a liquid to a gas at temperatures below the b.p.

Boiling: water at 100°C at sea level , some molecules below the surface of the liquid have enough kinetic energy to overcome the attraction of molecules. The water vapor is less dense than the liquid so rises. At surface they burst and release water vapor into the air.

Condensation: the phase change in which a substance changes from a gas or vapor into a liquid.

Sublimation: is the phase change in which a substance changes from a solid to a gas. (endothermic) dry ice

Deposition: when a gas or vapor changes directly into a solid without first changing to a liquid. (exothermic) frost hale