BASIC CHEMISTRY – Part 2 / Name:Answer Key
Date: Pd:

PART 1: MIXTURES:

Fill in the blanks from the information provided on the presentation.

  • A mixture is two or more substances blended together (notbonded).
  • Each substance in a mixture keeps all of its chemical and physical properties.
  • Mixtures,unlike compounds, can be separated into their individual substances by physicalmeans.
  • Example: salt and water can be separated by evaporation.
  • A solution is a mixture of two or more substances, one dissolved in another.
  • Two parts of a solution are thesolute and the solvent.
  • Solute – substance being dissolved
    Examples: sugar, salt
  • Solvent – substance doing the dissolving
    Example: water
  • A solution becomes saturated when the solvent holds all the solute that it can. It can nolongerdissolve solute.
  • Suspensions are a mixture of particlesscattered throughout another. The particles donotdissolve. Examples: clouds, dust, fog, smoke, mud, blood

Reflect:

  1. Give another example of solutions including the solute and solvent.
    Vinegar and Calcium Carbonate, etc…
  2. Can solutions be separated by chemical means?
    Perhaps, but will still involve physical separation as well

PART 2: COMPOUNDS

Compounds are two or more elements chemically joined by bonds.

They are represented by chemical formulas.

Properties of compounds are usually different than the atoms.
Example: Hydrogen(gas) + Oxygen(gas) = Water (liquid)
Example: Iron + Oxygen= Rust

Compounds can be separated into their elements only if the chemical bonds are broken. This can be done by chemical means (chemical reaction)

A molecule is the smallest part of a compound—like water—that has all the properties of the compound.

PART 3: REVIEW COMPOUNDS AND ELEMENTS

Write “E” for element or “C” for compound or B for BOTH for each description below:

  1. __C__ Two or more elements combined
  2. __E__Made up of one type of atom
  3. __E__Cannot be chemically broken down
  4. __C__ Table Salt (NaCl)
  5. __E__Sodium (Na)
  6. __C__ Glucose
/
  1. __C__ Water (H2O)
  2. __B__Smallest unit of a substance
  3. __E__Smallest unit of matter
  4. __B__Units of matter
  5. __E__Hydrogen (H)
  6. __C__Can be broken down chemically

PART 4: FORMATION OF CHEMICAL BONDS

  • A covalent bond is a bond formed when atoms shareelectrons to form a compound.
  • Strongphysical bond


  • An ionic bond is formed by the transfer of electrons from one atom to another.
  • It is a weak electrical attraction, not a physical bond.

Example: table salt (NaCl)

Sodium / Chlorine
Before
11 p+
11 e-
0
After
11 p+
10 e-
+1 /
(+) / /
(-) / Before
17 p+
17 e-
0
After
17 p+
18 e-
-1
  • Instead of being neutral, atoms of sodium and chlorine making up salt become charged.
  • Ions are charged atoms that havegained or lostone or moreelectrons.

BASIC CHEMISTRY – Part 2 (page 2) / Name: Answer Key
Date: Pd:

PART 5: CHEMICAL REACTIONS

  • A chemicalreaction is the process of breaking down existing chemical bonds of compound and formingnew bonds.
  • Elements combine in ways that cause their atoms to be stable.
  • The energy required to start a chemical reaction is activation energy and the most common form of this energy is heat.
  • A reaction that gives off more energy than it uses up is an exothermic reaction.
  • A reaction that gives off less energy than it uses up is an endothermic reaction.
  • Living things need a constant supply of energy from food because all cells use more energy than they produce.
  • Example reactions:
    Photosynthesis

Water + Carbon Dioxide Glucose (Sugar) + Oxygen.

H2O + CO2  C6H12O6 + 6O2

Respiration (Breathing)

Oxygen + food(glucose)  water + carbon dioxide

6O2 + C6H12O6  H2O + CO2

Rusting, Burning, Digestion, etc…

Reactants are on the left.

Products are on the right.

Questions:

  1. List and describe the major kinds of chemicals.
    Mixture – two or more blended substances
    Solution – A solute with a solvent dissolved in it
    Compound – two or more bonded substances
  2. What is the difference between an ionic and covalent bond?
    Covalent bonds are strong physical bonds where atoms share electrons.
    Ionic bonds are weak electrical bonds where atoms transfer electrons.
  3. Are mixtures formed during a chemical reaction? Why or why not?
    Mixtures are not formed during a chemical reaction because no bonds are being broken or formed.
  4. How are mixtures, compounds, andchemical reactions important for living things?