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CRCT Matter Review . Distinguish between atoms and molecules. atom (page 313) smallest unit of an element that maintains the properties of the element. Two parts. nucleus (page 316) – tiny, extremely dense, positively charged, center of the atom contains most of mass
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Distinguish between atoms and molecules • atom (page 313) • smallest unit of an element that maintains the properties of the element.
Two parts • nucleus (page 316) – tiny, extremely dense, positively charged, center of the atom • contains most of mass • electron cloud (page 317) – regions where electrons are likely to be found • contains most of volume • The atom is mostly empty space.
atomic number • Number of protons= number of electrons • Identifies the element. • Locate on the periodic table. • How many protons does carbon have? • How many electrons does carbon have? • What element has 20 protons? • What element has 16 electrons?
Answers • How many protons does carbon have? (6) • How many electrons does carbon have? (6) • What element has 20 protons? (calcium) • What element has 16 electrons? (sulfur)
molecule • Two or more atoms bonded together
Describe the difference between pure substances(elements & compounds)and mixtures.
Summarize • Substances cannot be broken down by physical changes. • Elementscannot be broken down (by physical or chemical means). • Compoundscan be broken down by chemical reactions. • Mixtures (combination of two or more substances that are not chemically combined). They can be separated by physical changes.
What is this? Find an atom a molecule a compound
Can it be separated by physical means? yes no substance mixture Can it be separated by chemical means? Is it uniform? no yes no yes compound element homogeneous heterogeneous Aka: solution Examples:colloid suspension Examples: Examples: Examples:alloy,
Describe the movement of particles in solids, liquids, gases and plasmas.
A change in state is a physical change. (Pages 74-79) solid melting deposition sublimation freezing condensation liquid gas evaporation, boiling
Heating Curve warming the gas boiling pointcondensationpoint boiling (liquid & gas) melting point/freezing point warming the liquid melting (solid & liquid) Temperature warming the solid Time heating
plasma • Add enough energyso some electronsare removed (free). • Positive atomfragments (ions)remain.
Distinguish between physical and chemical properties of matter • Physical properties can be observed directly without changing the identity of the matter. • Chemicalproperties cannotbe observed directly without changing the identity of the matter.
Physical properties • state of matter • melting point • boiling point • conductor - insulator • soluble – insoluble • ductile • malleable • brittle • texture • hardness • density • temperature
Chemical Properties • reactivity • Will it rust or tarnish? • Flammable or nonflammable?(Inflammable is not the antonym) • Combustible or incombustible?
Distinguish between physical and chemical changes in matter • Physical changes: identity of the matter does NOT change. • Chemical changes: identity of the matter changes.
physical changes • changes in state (melting, freezing, boiling, evaporation, condensation, sublimation, deposition) • cutting, chopping • crushing • sanding smooth • dissolving • clay changing shape
chemical change • aka: chemical reaction • burning/combustion • rusting/tarnishing • one substance another substance
evidence of a chemical change • gas formation • solid (precipitate) formation • color change
Recognize that there aremore than 100 elements and some have similar properties as shown on the Periodic Table of Elements.
PERIODIC TABLE DATA SHEET group, family (similar characteristics) period, series nonmetals metals Physical Characteristics metalloids dull, brittle, insulators luster, conductors (heat & electricity), ductile, malleable metalloids Si = semiconductor
Law of Conservation of Matter • Matter cannot be created or destroyed in an ordinary chemical or physical change. • mass at beginning = mass at the end.