Matter Vocabulary Notes

Chemistry

The study of matter and the changes matter undergoes.

Definite PropertiesA substances with definite properties means that the properties will not change under normal circumstances.

Ex: The boiling point of pure water is 100oC at sea level always

CompositionThe composition describes the elements that make up the substance or compound.

Fixed Composition

If a substance has a fixed composition, then it contains the same elements in the same ratios (amounts). (compounds, pure substances, elements only)

Ex: Water contains 2 hydrogens and 1 oxygen always (H2O)

Pure SubstanceCannot be separated physically.

Combined and separated by chemical processes (reactions).

Elements and compounds

Represented by chemical formulas

Pure Substances

Same amount of the same atoms always (fixed composition)

Definite properties

Mixtures

Composition and properties may change due to varying amounts of substances.

Physically combined and separated (ex: chex mix)

CANNOT be represented by a chemical formula.

MixturesHomogeneous Mixtures – evenly mixed, uniform throughout. (cannot see different components)

Ex: Kool-Aid, Salt Water

Heterogeneous Mixtures – not evenly mixed, non-uniform. (can see different components)

Ex. Pizza, Salsa, Salad

ElementsSimplest form of matter that retains its properties.

Cannot be broken down into a simpler substance

Composed of atoms

Can be solids, liquids, or gases. (most are solids at room temp)

Elements

Elements all have a chemical symbol.

Ex. Copper, Cu Oxygen, O

Compounds

Chemical combination of elements with a fixed composition.

Compounds have definite properties and fixed compositions.

Ex) Water is always made up of 2 hydrogen atoms and 1 oxygen atom.

CompoundsCompound properties usually differ from the elements in the compound.

Ex. Hydrogen and oxygen are both flammable gases; water is nonflammable liquid.

• All compounds have a chemical formula that never changes.• Ex. Water, H2O Ammonia, NH3

Compounds

Smallest unit is known as a molecule (more than 1 atom)

SolutionsAll solutions are homogeneous mixtures.

Evenly mixed, uniform throughout

No chemical formula b/c composition may change.

SolutionsContain a solute and solvent.

Solute – substance that is dissolved in the solution.

Solvent – substance that dissolves the solute.

Ex: Kool-Aid: The sugar and powder are solutes, and the water is the solvent.

Venn Diagram

Using our discussions you must create a Venn diagram for Compounds and mixtures. You need at least 3 similarities in the center region. Each circle needs 5 pieces of info.

States of Matter

What can you tell me about solids?

What can you tell me about liquids?

What can you tell me about gases?

SolidsDefinite shape and definite volume

Particles are tightly packed due to strong attractions.

Particles do not have enough energy to break those attractions.

Solids

Usually the densest form of matter. (higher densities than other states).

Particle movement is limited to vibrating in place.

Energy must be added to break attractions.

Liquids

Definite volume; take the shape of its container.

Particles have weaker attractions, but still keep particles in constant contact.

Particles may slide passed one another, but cannot break free.

Liquids

Particles have enough energy to overcome some of the attraction in order to move.

Densities are generally less than solids, and more than gases.

Adding more energy will completely overcome attractions.

Gases

Particles are free to move because the attractions are so small, we say there are no attractions.

Particles are in constant, random motion.

Particles have enough energy to break free from the weak attractions.

Gases

Gases take the shape and volume of their container.

The density of a gas is usually very low; much lower than solids and liquids.

The particles move faster when energy is added.

Gas LawsThe gas laws demonstrate the relationships among the following variables: pressure, volume, and temperature.

We must know how changing one variable affects the others.

Focus on how the molecules move and a little common sense.

Pressure and Volume

The pressure of a gas is a result of the collisions of the molecules with the sides of the container.

Pressure and volume are inversely proportional.

If the volume decreases, then the pressure will go up.

The molecules will have less room to move, so there are more collisions.

Temperature and Pressure

As the temperature increases, the molecules have more kinetic energy, so they move more resulting in more collisions.

Temperature and pressure are directly proportional.

More energy = more collisions = higher pressure.

Temperature and volume

When the molecules have more energy, they need more space to move to maintain a constant pressure.

As the temperature rises, the volume must also increase to reduce the number of collisions.

Temperature and volume are directly proportional.

Laws of conservation

Mass is not created or destroyed during any physical or chemical process.

Energy is not created or destroyed during any physical or chemical process.

Energy’s RoleAdding or releasing energy can change the state of matter of a substance. (physical change)

Changing the state of matter does not change the composition.

Ex: Liquid water and ice (solid) are both H2O even though they are different states of matter.

Energy’s Role

Temperature – A substance’s temperature is the average kinetic energy of the molecules.

Transferring energy (heat) changes the substance’s temp.

Energy’s Role

Adding energy results in

Melting:

Evaporation:

Sublimation:

Energy’s Role

Releasing energy results inCondensation:Freezing:

Freezing and melting happen at the same temp!

Phase Diagram

Demonstrates how energy and pressure may change the state of matter.