Unit 4: Interactions of Matter – Review Notes
Main Idea
1. What is a chemical?
name:_______________________
period: ______________
Supporting Details/Answer
Anything made of matter is a chemical.
2. What is a chemical formula?
A short way of writing chemical symbols for
atoms that have bonded together. (e.g. H20)
3. How can you use chemical symbols and
numbers in a chemical formula to figure
out how many atoms of different elements
are bonded? (e.g. C6H12O6)
Use the periodic table to determine the name of an
element based on its symbol.
Numbers (called subscripts) tell you how many
atoms of the element are present. The number
refers to the symbol to the left.
4. How many types of mixtures are there?
3 types of mixtures
5. List the different types of mixtures and
describe them.
Solution: very small particles, homogeneous, no
light scattering, no particle settling
Colloid: small particles, homogeneous, light
scattering, no particle settling
Suspension: larger particles, heterogeneous, light
scattering, particle settling
Heterogeneous (hetero = other, generous = kind):
possible to see the different parts of a mixture (e.g.
trail mix)
Homogeneous (homo = same, generous = kind):
appears to be a single substance (e.g. salt water)
Solutions and colloids: evaporation; the particles are
not chemically combined, so evaporating one of
them will leave the other; particles are too small to
filer
Suspension: filters, mechanical separation (e.g.
tweezers), magnets, screens, etc. ; particles are big!
Solute: The substance that is dissolved into a solvent to
6. What does it mean for a mixture to be
heterogeneous or homogeneous?
7. How can you separate the different types
of mixtures? Why do these methods work?
8. What are solutes and solvents? Give an
example.
9. What does it mean for a chemical to be
“soluble”? (e.g. solubility is the ability of a
chemical to…) Is solubility a physical or
chemical property of matter?
10. Describe what is happening when a solute
dissolves in a solvent. Is this a physical or
form a solution. (Kool-Aid powder in Kool-Aid)
Solvent: The substance in which a solute is dissolved to
form a solution. The chemical that is the greatest
amount. (Water in Kool-Aid)
The chemical has the ability to dissolve in another
substance. Solubility is a physical property of matter.
Dissolving salt into water does not create a new
substance through chemical bonding. The particles are
dispersed without bonding.
Dissolving is a physical change where the particles of
the substances mix equally but do not chemically
Unit 4: Interactions of Matter – Review Notes
name:_______________________
period: ______________
chemical change? Is a new chemical
formed or do the substances equally
disperse? Draw a picture.
combine.
11. Why do chemical equations need to be
balanced?
Chemical equations need to be balanced because all
of the ingredients (reactants) must be present in the
products. In chemical reactions, no atoms are
created or destroyed. Bonds between atoms are
created and destroyed. The Law of Conservation of
Mass states that all atoms must be accounted for.
12. Practice balancing equations:
http://funbasedlearning.com/chemistry/chembalancer/
http://www.chem.vt.edu/RVGS/ACT/notes/scripts/bal_eq1.html
13. Describe the Law of Conservation of Mass
In regular chemical and physical changes, no matter
and how it applies to chemical and physical (mass) can be created or destroyed. This means that
changes.
even though atoms may move or recombine to form
new substances (chemical) or change form
(physical), all of the atoms must be accounted for.
Example: 1 block of cheese = 100g ; cut it into two
pieces and together, the pieces will still = 100g
14. What are properties of matter?
Properties of matter are ways of describing matter.
15. Define chemical property of matter:
16. Define physical property of matter:
17. What are some clues of a chemical
reaction?
18. What are the three possible outcomes
when mixing chemicals together?
19. How can you slow down or speed up a
reaction?
A chemical property of matter can only be observed
by reacting matter with other matter to create a
new type of matter. Chemical properties describe
the ability of a type of matter to react with other
matter.
A physical property can be observed without
changing the matter into a new substance. (color,
texture, density, solubility, state of matter, etc.)
Clues: bubbling, foaming, new gas formed,
precipitate (new solid), energy change (hot, cold,
light, explosion, etc.), unexpected color or odor
change
There are three main outcomes: mixing, non-mixing,
and chemical reaction.
Speed up: add energy (heating); increase surface
area (stirring, crushing); adding a catalyst (chemical
that helps the reaction go faster)
Slow down: remove energy (cool down); decrease
Unit 4: Interactions of Matter – Review Notes
name:_______________________
period: ______________
surface area
20. Describe the role energy plays in chemical
changes.
All reactions need energy to get started.
Exothermic: releases energy (feels hot, emits light;
etc.)
Endothermic: continues to absorb energy (feels
cold)
21. How are physical and chemical changes
Physical Change: easier to reverse; can be reversed
different?
with a physical change; changes physical properties
of a chemical; no new substance formed
Chemical Change: results in a new substance;
chemical change needed to reverse; original
substances do not maintain properties; new
substance has new properties
22. How are atoms, elements, compounds,
Atom: basic unit of matter
molecules and mixtures similar and
Element: specific types of atoms with different
different? Draw a picture or use symbols to numbers of protons, electrons, and neutrons and
illustrate.
physical/chemical properties (O, C, H or O2)
Compound: 2 or more different elements chemically
bonded to make a new substance (CO2)
Molecule: elements chemically bonded; can be a
new substance (H20) or same substance (O2);
characterized by covalent bonds (not covered in
class)
Mixture: 2 or more substances combined without
chemical bonds
23. Describe the process of making new
When two or more substances react to make a new
substances. What happens to chemical
substance, the bonds between atoms may be
bonds and what do we need to make new
broken. This takes energy. The original atoms may
substances?
move around to recombine with different atoms.
New bonds are formed which takes energy. The new
substance(s) (products) are different than the
original substances (reactants). No atoms are
destroyed in the process due to the Conservation of
Mass. This chemical reaction can be written by a
chemical formula.