crct matter review. distinguish between atoms and molecules atom (page 313) smallest unit of an...
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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.