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 electron cloud (page 317) – regions where electrons are likely to be found contains most of volume The atom is mostly empty space.

Particle Symbol Location Charge proton p+ nucleus 1+ neutron no none (0) electron e- electron cloud 1-

Number of protons = number of electrons Identifies the element. 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.

Substances cannot be broken down by physical changes. Summarize Substances cannot be broken down by physical changes. Elements cannot be broken down (by physical or chemical means). Compounds can 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.

http://www.chem.ufl.edu/~itl/2045/lectures/lec_f.html

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 (liquid & gas) boiling point condensation point boiling (liquid & gas) melting point/ freezing point warming the liquid Temperature melting (solid & liquid) warming the solid Time heating

plasma Add enough energy so some electrons are removed (free). Positive atom fragments (ions) remain.

Distinguish between physical and chemical properties of matter Physical properties can be observed directly without changing the identity of the matter. Chemical properties cannot be 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 are more 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 Group number & name 1 alkali 2 alkaline earth 3-12 transition element 13 14 15 16 17 halogen 18 noble gases colorless odorless gases Physical Characteristics metals nonmetals 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.