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IV. LESSON 4
Unit 1 – Lessons 1-6 “Describing Matter” (Pages 4-87)
A. Pure Substances and Mixtures
1. ALL matter is composed of particles called ATOMS
2. Atoms form ELEMENTS and come together in different ways to form COMPOUNDS and
MIXTURES
3. ATOM  SMALLEST unit of an ELEMENT and maintain the PROPERTIES of that element
4. MOLECULE  SMALLEST unit of a COMPOUND; maintaining PROPERTIES of the compound
5. ELEMENT  matter that is composed of one kind of ATOM (e.g. sulfur [S]; carbon [C])
a. each ELEMENT has its own CHARACTERISTIC chemical and PHYSICAL properties
*b. elements can NOT be BROKEN down into other substances by any CHEMICAL means
c. some MATTER exists in elemental form [(e.g.) gold [Au] = not chemically REACTIVE)]
*d. ELEMENTS individually or combined form everything in the universe including HUMANS
*1. Human body’s most abundant ELEMENTS: carbon [C], oxygen [O], hydrogen [H],
and nitrogen [N]; for teeth & BONES = calcium [Ca] and phosphorus [P]; for
taste buds = zinc [Zn]; for nervous system = copper [Cu]; for blood = iron [Fe]
*e. There are currently 118 known ELEMENTS and 92 are found in nature, while the others
are SYNTHETICALLY (man-made), but we only use between 30-40 elements daily
*1. The discovery of all the ELEMENTS to date has taken THOUSANDS of years
*2. In ancient times, it was believed there were “4” ELEMENTS: water, air, land, fire
*f. The chemical symbol of an ELEMENT  is a shorthand form of the element’s NAME
*1. The chemical SYMBOL always BEGINS with a CAPITAL letter, with any other
letter(s) written in their LOWER-CASE form
*a. (e.g.) sulfur [S]; iodine [I]; fluorine [F]; helium [He]; gallium [Ga]
*2. Some elements’ CHEMICAL symbols are based on their Latin, Greek or Arabic name
*a. (e.g.) gold [Au]; silver [Ag]; mercury [Hg]; tin [Sn]; lead [Pb]
6. COMPOUND  substance composed of two or more kinds of ATOM that has been CHEMICALLY
combined (e.g. sodium chloride [NaCl]; hydrogen peroxide [H2O2]; iron oxide [Fe2O3])
a. every COMPOUND has its own distinct PROPERTIES
1. the PROPERTIES of a compound differ from the PROPERTIES of the individual
ELEMENTS making up the COMPOUND
a. (e.g.) sodium [Na] and chlorine [Cl] individually have totally DIFFERENT
properties compared to the COMPOUND sodium chloride [NaCl]
b. MOST matter on Earth exists in the form of a COMPOUND
*c. When a COMPOUND forms, it ALWAYS contains the SAME elements and the SAME
number of atoms per ELEMENT in exactly the SAME ratio
*1. WATER = is always composed of the ELEMENTS hydrogen [H] and oxygen [O]
with a 2:1 ratio of atoms respectively  H2O
*2. HYDROGEN PEROXIDE = is always composed of the ELEMENTS hydrogen [H]
and oxygen [O] with a 2:2 ratio of atoms respectively  H2O2
*d. A chemical formula  is a chemical abbreviation for writing a COMPOUND
*1. A formula includes: CHEMICAL symbols of the ELEMENTS and numbers written
as subscripts to show the ratio of ATOMS per ELEMENT
*a. If an ELEMENT has NO subscript, the SUBSCRIPT is understood to be “1”
*b. (e.g.) carbon monoxide [CO]; carbon dioxide [CO2]; ammonia [NH3]
*e. Examples of COMPOUNDS:
*1. Table salt = NaCl [sodium, chlorine w/1:1 atom ratio]
*2. Sand = SiO2 [silicon, oxygen w/1:2 atom ratio]
*3. Table sugar = C12H22O11 [carbon, hydrogen, oxygen w/12:22:11 atom ratio]
*4. Glucose = C6H12O6 [carbon, hydrogen, oxygen w/6:12:6 atom ratio]
*5. Chalk = CaCO3 [calcium, carbon, oxygen w/1:1:3 atom ratio]
*6. Iron oxide (rust) = Fe2O3 [iron, oxygen w/2:3 atom ratio]
*7. Baking soda = NaHCO3 [sodium, hydrogen, carbon, oxygen w/1:1:1:3 atom ratio]
*f. COMPOUNDS can be broken down, but because the elements were CHEMICALLY joined
together, a CHEMICAL process is necessary to SEPARATE them.
*1. Heating breaks down some COMPOUNDS: iron separated from oxygen
(e.g.) 2 Fe2O3 + 3 C (are heated)  4 Fe + 3 CO2 (the IRON [Fe] is SEPARATED)
*2. Electrolysis is an ELECTRIC current passed through some COMPOUNDS to break
them down: water is broken down into HYDROGEN gas [H2] and OXYGEN gas [O2]
(e.g.) 2 H2O (electricity is added)  2 H2 + O2 (the HYDROGEN [H] and OXYGEN [O]
are SEPARATED)
*3. Some COMPOUNDS are so UNSTABLE that they break down without the use of
HEAT or ELECTROLYSIS
*a. LIGHT acts as a catalyst (something that SPEEDS up a reaction) and is all that is
needed to break down an UNSTABLE compound: hydrogen peroxide [H2O2] is
broken down into WATER [H2O] and OXYGEN gas [O2]
(e.g.) 2 H2O2 (exposed to light)  2 H2O + O2 (DECOMPOSED into water and oxygen)
7. MIXTURE  is matter that has been MIXED or blended together PHYSICALLY, but NOT
CHEMICALLY combined
a. since MIXTURES are NOT CHEMICALLY joined together, each substance retains its
PHYSICAL and CHEMICAL properties
*b. MIXTURES, however, do NOT require a specific RATIO of substances
*1. Sugar water = is composed of the SOLUTE (substance being dissolved) sugar and the
SOLVENT (substance doing the dissolving) water
*a. Add more sugar (SOLUTE), the solution becomes CONCENTRATED
*b. Add LESS sugar (SOLUTE), the solution becomes DILUTED
B. Pure Substances: ELEMENTS and COMPOUNDS
1. Two types of PURE substances:
 ELEMENTS (e.g.) potassium [K]; aluminum [Al]; sodium [Na]
 COMPOUNDS (e.g.) SALT [NaCl]; glucose [C6H12O6]; TABLE SUGAR [C12H22O11]
2. Pure substances have definite CHARACTERISTIC physical and chemical PROPERTIES
a. Properties of PURE substances remain consistent because the most basic particles (ATOMS and
MOLECULES) making up each substance are IDENTICAL [(e.g.) copper [Cu]; water [H2O] ]
3. CHEMICAL bonds (ionic and covalent bonds) are FORCES that hold the ATOMS together that
form COMPOUNDS and can only be broken by a CHEMICAL change (electrolysis, heat, light)
4. Classifications of PURE substances are according to their PROPERTIES
a. ELEMENTS are classified into 3 groups: METALS, NON-METALS and METALLOIDS
*1. METALS (metallic) have the following PROPERTIES:
*a. LUSTER  the amount of SHINE or brightness (e.g.) chromium [Cr]
*b. MALLEABLE  able to be hammered, rolled, or shaped without BREAKING
(e.g.) copper (Cu); gold [Au]; aluminum [Al]
*c. DUCTILE  able to be drawn into a WIRE (e.g.) tungsten [W]; platinum [Pt]
*d. Good CONDUCTORS of HEAT  items made from these elements heat quickly
and distribute the heat evenly (e.g.) iron [Fe]; aluminum [Al]
*e. Good CONDUCTORS of ELECTRICITY  metals through which electrons move
freely forming ELECTRIC currents (e.g.) gold [Au]; copper [Cu]; tungsten [W]
*f. STATE of MATTER at room temperature (25o C)  most metals are a SOLID at
room temp; except mercury [Hg]; copernicium [Cn], which are LIQUIDS at 25o C
*g. Some METALS exist for a short period of time in pure form (e.g.) francium [Fr]
*2. NON-METALS (non-metallic) elements’ PROPERTIES:
*a. STATE of MATTER at room temperature (25o C)  nonmetals are a SOLID or
GAS at room temperature, except bromine [Br], only LIQUID non-metal at 25o C
*1. Nonmetals have “OPPOSITE” properties of metals: low or no LUSTER,
poor conductors of HEAT /electricity, and not ductile or MALLEABLE
*3. METALLOIDS, the “6” elements that BORDER between the METALS and
NONMETALS, having properties “BETWEEN” those of METALS and NONMETALS
*a. Common metalloids:
*1. silicon [Si] – combined with oxygen forming sand [SiO2], glass and cement
*2. boron [B] – is used in CLEANING solutions
*3. arsenic [As] – is a POISON
*b. Metalloids CONDUCT electricity LESS efficiently than METALS, but MORE
efficiently than NON-METALS
*1. silicon [Si] and germanium [Ge] – are used as semi-conductors to make
computer chips, transistors, and LASERS
*c. Two other METALLOIDS are: ANTIMONY [Sb] and TELLURIUM [Te]
*d. ALUMINUM [Al] although it borders the line that SEPARATES the metallic
from the non-metallic ELEMENTS; it is definitely a METAL
*e. ASTATINE [At] and POLONIUM [Po] also border the zigzag line, but are still
being debated as to whether they are METALLOIDS
b. COMPOUNDS can be classified as a BASE, ACID, or NEUTRAL substance based on their
“pH” value (determined using a LITMUS indicator):
 ACIDS have a pH value BELOW “7”; (e.g.) vinegar [CH3COOH]; litmus turns RED
 BASES have a pH value ABOVE “7”; (e.g.) baking soda [NaHCO3]; litmus turns BLUE
 NEUTRAL substances’ pH value is “7”; (e.g.) distilled water [H2O]; litmus NO change
c. COMPOUNDS can also be classified as ORGANIC or INORGANIC
1. ORGANIC compounds have chemical bonds between carbon [C] & hydrogen [H] atoms
a. ORGANIC compounds made from BIOTIC matter are called BIOCHEMICALS
1. Four categories of BIOCHEMICALS:
a. CARBOHYDRATES: a macronutrient and source of ENERGY
(e.g.) sugar, starch, fiber
b. LIPIDS: a macronutrient that stores EXCESS energy and forms
CELL membranes (e.g.) FATS, oil, wax
c. PROTEINS: a macronutrient that regulates body CHEMICAL
activities; builds and REPAIRS cellular structures
d. NUCLEIC ACIDS: contain genetic information (e.g.) DNA and RNA;
build PROTEINS
C. Mixtures
1. MIXTURE  consists of TWO or more substances that are MIXED / BLENDED together, but do
NOT react CHEMICALLY to form a NEW substance, instead keeping their original PROPERTIES
2. Mixtures are not PURE substances
3. Components of a MIXTURE are NOT all IDENTICAL and do NOT have DEFINITE properties
because they do NOT have a defined CHEMICAL makeup
4. Mixtures can be SEPARATED by PHYSICAL means which depends on their physical and
chemical PROPERTIES
*a. Methods used to separate the substances of MIXTURES are:
 PHYSICAL separation the substances (e.g. remove mushroom topping from pizza)
 FILTERING various sized particles (e.g. sifting dirt particles)
 MAGNETIZISM force of attraction or repulsion between MAGNETIC materials
*1. (e.g.) iron [Fe – most MAGNETIC element ] nails from aluminum [Al] nails)
 DENSITY can separate substances NATURALLY (e.g. sand in water)
*1. CENTRIFUGE machine (e.g. separates parts of BLOOD)
 DISTILLATION is the process of BOILING away water or letting water EVAPORATE
(the 2 forms of vaporization) from a SOLUTION, leaving the SOLID that was
DISSOLVED as a residue
5. MIXTURES are classified into two types: HOMOGENEOUS and HETEROGENEOUS
a. HOMOGENEOUS  the substances are EVENLY dispersed throughout the MIXTURE due
to the DIFFUSION (going from areas of HIGH concentration to areas of LOW
concentration) of the particles throughout the mixture
1. Particles are extremely SMALL; they will NOT settle out; ALWAYS stay MIXED
2. SOLUTION  homogeneous mixture where one substance is DISSOLVED in another
*a. Types of SOLUTIONS:
*1. the most common SOLUTION is a SOLID dissolved in a LIQUID
*a. (e.g.) SUGAR (solute – the substance being dissolved) and water
(solvent – the substance that dissolves other materials)
*2. one LIQUID dissolved in another LIQUID
*a. (e.g.) Ethylene glycol (solute) and WATER (solvent) to make
ANTIFREEZE (FREEZING pt = -13o C; BOILING pt = 176 o C)
*3. a GAS dissolved in a LIQUID
*a. (e.g.) CARBON DIOXIDE gas (solute) and soda (solvent) to make a
carbonated soft drink
*4. a GAS dissolved in another GAS
*a. (e.g.) AIR is a mixture of nitrogen [N] (solvent), oxygen [O], argon
[Ar] and carbon dioxide [CO2] (solutes)
*b. ALLOYS  are solid SOLUTIONS of metals DISSOLVED in other metals
and non-metals dissolved in METALS
*1. Steel  is a SOLUTION of metal iron [Fe] and non-metal carbon [C];
exceptionally strong
*2. Bronze  is a SOLUTION of metal copper [Cu] and metal tin [Sn];
earliest of the alloys
*3. Brass  is a SOLUTION of metal copper [Cu] and metal zinc [Zn];
very malleable
*4. Sterling silver  is a SOLUTION of metal silver [Ag] and metal copper
[Cu]; harder and does NOT tarnish like pure silver [Ag]
*5. Solder  is a SOLUTION of metal tin [Sn] and metal lead [Pb]; LOW
MELTING point and is used to join METALS together
*6. Wood’s metal  is a SOLUTION of metal bismuth [Bi], metal lead [Pb],
metal tin [Sn], and metal cadmium [Cd]; used in
sprinkler systems in buildings
*c. Concentration  is a way to describe a SOLUTION because different amounts
of SOLUTE can be DISSOLVED in different amounts of SOLVENT
*1. DILUTE  are solutions with a SMALL amount of SOLUTE
*a. (e.g.) “WEAK” tea (lighter in COLOR; weaker TASTE)
*2. CONCENTRATED  are solutions with a LARGE amount of SOLUTE
*a. (e.g.) “STRONG” tea (DARKER in color; STRONGER taste)
*d. Solubility  is a MEASURE of how well a SOLUTE can DISSOLVE in a
SOLVENT at a given TEMPERATURE
*1. SOLUBLE  SOLUTES that will dissolve in a SOLVENT
*2. INSOLUBLE  SOLUTES that will NOT dissolve in a SOLVENT
*3. SATURATED  are solutions with so much SOLUTE that no more will
DISSOLVE
*4. UNSATURATED  are solutions where MORE solute will continue to
DISSOLVE when added to the SOLVENT
*5. SUPERSATURATED  are solutions containing more SOLUTE than the
SOLVENT at a given temperature can DISSOLVE
*6. For many solids, solubility INCREASES as the temperatures RISE, because a
solid’s particles move FASTER and spread FARTHER apart allowing more
room in the SOLVENT for MORE dissolved particles
*a. (e.g.) Potassium nitrate [KNO3] and POTASSIUM chloride [KCl]
*7. For many gases, an INCREASE in temperature DECREASES the solubility
of a gas in a liquid, because the speed of the dissolved gas particles
INCREASES, causing the particles to gain energy and LEAVE the solution
more readily.
*a. (e.g.) Bubbles of DISSOLVED air escape long before the water boils,
because water is able to hold LESS air in solution as its temperature
INCREASES
*e. Effects of Solutes on Solutions
*1. Lower the Freezing Points  Solutes LOWER the FREEZING point of a
SOLVENT, because the SOLUTE particles interfere with the SOLVENT’S
particles making it HARDER for the water molecules to form CRYSTALS.
*a. (e.g.) A salt water SOLUTION – the temperature must drop lower
than 0o C for water to FREEZE and for a SOLID to form
*2. Higher Boiling Points  Solutes RAISE the BOILING point of a
SOLVENT, because the SOLUTE particles make it HARDER for the water
molecules to gain energy and ESCAPE into the air.
*a. (e.g.) A salt water SOLUTION – temperature must go higher than
100o C for the water to gain more ENERGY for the water to BOIL
*f. Water [H2O] is the UNIVERSAL solvent for SOLUTIONS
*1. However, NOT all solutes DISSOLVE in water
*a. (e.g.) oil-based paints require TURPENTINE as the SOLVENT
b. HETEROGENEOUS  substances NOT evenly distributed throughout the MIXTURE
1. Particles are LARGER, can VARY in size and do NOT stay MIXED
2. SUSPENSION  heterogeneous mixture where particles of one substance are
SCATTERED throughout another substance and WILL eventually SETTLE out
*3. Types of SUSPENSIONS:
*1. solid particles SUSPENDED in a liquid
*a. (e.g.) sand in WATER; juices w/PULP; Italian SALAD dressing
*2. solid particles SUSPENDED in a gas
*a. (e.g.) dust or SMOKE particles in the AIR
*3. gas molecules SUSPENDED in a liquid
*a. (e.g.) AIR scattered in a “creamy” fluid to make shaving CREAM and
WHIPPED cream
*4. COLLOID  has MEDIUM - SIZED particles that remain MIXED in a gas, LIQUID
or SOLID
*a. Colloids appear to be SOLUTIONS, because their particles are well-mixed
and are too SMALL to be SEEN because they are DIFFUSED evenly in
another substance
*1. Colloids are HOMOGENEOUS in appearance
*b. a COLLOID’s particles are large enough, however, to “SCATTER” or
“SUSPEND” a beam of LIGHT, but a solution’s particles are NOT
*c. (e.g.) MILK, fog, TOOTHPASTE, gelatin and BLOOD
*d. SOLUTION versus COLLOID (Tyndall effect):
*5. EMULSION  is a special type of COLLOID that consists of one liquid SUSPENDED
in another LIQUID
*a. Emulsions are well-mixed substances and are therefore HOMOGENEOUS
*b. (e.g.) mayonnaise is an EMULSION of vinegar (LIQUID) SUSPENDED
in oil (LIQUID) and egg yolks (the emulsifier)
*c. EMULSIFIER  is a substance that keeps the particles in one LIQUID
MIXED in another LIQUID
*1. (e.g.) in mayonnaise the EMULSIFIER is the EGG YOLKS
*d. Many, but NOT all EMULSIONS have EMULSIFIERS