CRCT MatterReview

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 nucleus none (0)

electron e- electroncloud

1-

atomic number• Number of protons

= number of electrons• Identifies the element.• Locate on the periodic table.1) How many protons does carbon have? 2) How many electrons does carbon

have? 3) What element has 20 protons? 4) What element has 16 electrons?

Answers1) How many protons does carbon

have? (6) 2) How many electrons does carbon

have? (6) 3) What element has 20 protons?

(calcium) 4) 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.–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 1) an atom2) a molecule3) a compound

Can it be separated by physical means?

mixture

Is it uniform?

homogeneous heterogeneous

yes

substance

no

Can it be separated by chemical means?

yes no

Aka: solution

Examples:alloy,

Examples:colloid

suspension

compound element

yes no

Examples: Examples:

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

liquid gas

melt

ing

freez

ing

condensation

evaporation, boiling

sublimation

deposition

Heating Curve

Time heating

Tem

pera

ture

warming the solid

melting (solid & liquid)

melting point/freezing point warming the liquid

boiling (liquid & gas)

boiling pointcondensation

point

warming the gas

plasma• Add enough energy

so 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.

• 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 number

& name

1alkali

2alkalineearth

3-12transition element

13 14 15 16 17halogen

18noble gases

colorlessodorlessgases

Phy

sica

l Cha

ract

eris

tics

group, family (similar characteristics)

period, series

metals nonmetalsmetalloids

metalloidsluster, conductors (heat & electricity),ductile, malleable

dull, brittle,insulators

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.