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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.