6th Grade Science

Matter

•Anything that has a mass and a volume•Molecules are in constant motion

Close up view of atoms and their behavior

Animated images are from http://www.chem.purdue.edu/gchelp/

Solids•particles vibrate but can’t move around

• definite/fixed shape and volume

• crystalline - repeating geometric pattern (sugar, diamond, salt)

• amorphous - no pattern (e.g. glass, wax)

Liquids•particles can move around but are still close together; flow

• no definite shape but

definite volume

• takes the shape of its container

Gases•particles can separate and move throughout container

• No definite shape

• No definite volume

• Fills up whatever space is available

Plasma•particles collide with enough energy to break into charged particles (+/-)

• gas-like, no definiteshape & volume

• stars, fluorescentlight bulbs, lightning

Most matter expands when heated & contracts when cooled.

Temp causes KE. Particles collide with more force & spread out.

EX: thermostats (bimetallic strip)

Thermal Expansion

Phase Changes• Melting

▫ solid to liquid▫ Thermal energy increases

• Freezing

▫ liquid to solid

▫ Thermal energy decreases

melting point = freezing point

Phase Changes•Vaporization (boiling)

▫ liquid to gas at the boiling point▫occurs below the surface▫Thermal energy increases

•Vaporization (evaporation)▫ liquid to gas below the boiling point▫occurs at the surface▫Thermal energy increases

•Condensation▫gas to liquid▫Thermal energy decreases

Phase Changes•Sublimation

▫solid to gas▫Thermal energy

increases▫EX: dry ice,

freeze drying, iodine

A. Phase Changesdeposition

B. Heating Curves

•Kinetic Energy▫motion of particles▫related to temperature

•Potential Energy▫space between particles▫related to phase changes

B. Heating Curves

Solid - KE

Melting - PE

Liquid - KE Boiling - PE

Gas - KE

A. Physical Property

•A characteristic of a substance that can be observed without changing its identity.

▫can be used to separate mixtures

▫EX: magnetism, density, state of matter, mass, volume, melting/boiling points, solubility

D. Chemical Property

•A characteristic that indicates whether a substance can undergo a specific chemical change.

▫EX: flammability, reactivity, color change, coking/baking

•When a change occurs that does NOT produce a new substance a physical change occurs

•If a new substance is formed it is a Chemical Change.

Images are from http://www.chem4kids.com

B. Physical Change

•A change in the form of a substance without changing its identity.

▫properties remain the same

▫reversible

▫can be used to separate mixtures

▫EX: dissolving, grinding, tearing, changing state or shape

C. Chemical Change•A change in the identity of a substance.

▫properties change

▫irreversible

▫Signs: color change, formation of a gas/solid, release of light/heat

▫EX: burning, rusting

• The building blocks of Matter• Consists of Protons (+), Electrons (-), and Neutrons (N).

• Consists of only one kind of atom, • Cannot be broken down into a simpler type of matter by either physical or chemical means• Can exist as either atoms or molecules.

• A molecule consists of two or more atoms of the same element, or different elements, that are chemically bound together. • In the animation above, two nitrogen atoms (N + N = N2) make one Nitrogen molecule .

• Atoms of two or more different elements bound together.

• Can be separated into elements chemically, but not physically.

In the animation above, water (H20) is a compound made of Hydrogen and Oxygen.

• Solutions are groups of molecules that are mixed up in a completely even distribution.

• Uniform Distribution.• Example: Sugar and Water

• The substance to be dissolved.

• The one doing the dissolving.

• Particle sizes are in between the size of particles found in solutions and suspensions .

• Can be mixed and remain evenly distributed without settling out.

• They are substances held together by physical forces, not chemical.

• Can be separated physically.

• Solutions are also mixtures.

• The substances are not uniformly mixed.

• Example: Sand in a glass of water.

• Are heterogeneous mixtures consisting of parts that are visible to the naked eye.

Example: the ingredients in salad dressing

• Substances will settle over time.