Science 10 Chemistry Unit Review – SOLUTIONS!

Terminology

1. Matter is anything that occupies space and has mass.

  1. The rows in the periodic table are called periods
  2. Electrons move rapidly around the nucleus in regions called electron shells (or electron cloud)
  3. Compounds and elements are both pure substances
  4. A(n) element is a pure substance that can’t be broken down into simpler substances by chemical means.
  5. Two molecules, such as oxygen, that are bonded together are called a(n) diatomic molecules.
  6. A(n) atom is the smallest particle of an element that can exist and still retain the ordinary chemical properties of that element.
  7. There are 18 groups in the periodic table. The group number determines the number of valence electrons.
  8. A(n) proton is a sub-atomic particle, within the nucleus of an atom, which has a mass of about 1 atomic mass unit and a positive charge.
  9. Transition metals are in groups 3 to 12. They share the normal properties of metals, however, their charges are not as easily predicted since some of them have two possible charges.
  10. Metals tend to lose electrons to become stable cations.
  11. The atomic number of an element is equal to the number of protons that each atom of that element has in its nucleus.
  12. Non-metals tend to gain electrons to become stable anions.
  13. A(n) neutron is a sub-atomic particle, within the nucleus of an atom, which is responsible for isotopes, and has a net charge of zero.
  14. Metalloids are located one the “staircase”. Their properties are in between those of metals and non-metals.
  15. The mass number of an atom is the number of protons and neutrons it has in its nucleus.
  16. A(n) electron is a sub-atomic particle, outside the nucleus of an atom, which has a mass of nearly zero and a negative charge.
  17. A(n) compound is a pure substance which contains 2 or more different elements chemically bonded together.
  18. A(n) mixture consists of 2 or more substances which are not chemically bonded together.
  19. Valence electrons are the only ones directly involved in either covalent or ionic bonding.
  20. Ionic bonds are created by the force of attraction between two oppositely charged ions.
  21. If an ion has a negative charge, this means there are more electrons than protons; the ion is likely a(n) non metal.
  1. Physical properties usually involve one of the five senses. Examples include colour, texture and smell.
  2. Noble gases are located in group 18 and are best known for their stability (full valence shell).
  3. If an atom has the same number of protons as electrons, then it is neutrally charged, however if it has more protons than electrons it is a positively charged ion.
  4. Halogens are located in group 17. They react easily by gaining one electron(s), thus forming negatively charged ions called anions.
  5. Metals are shiny, malleable and ductile solids.
  6. Metals want to lose electrons while non-metals will gain or share electrons in order to form bonds.
  7. Alkali metals are located in group 1. They are very unstable; they form positively charged ions by losing one electron(s).

Part 3: Applying your Knowledge

  1. For each of the following properties, determine if it applies to a metal or a non-metal. Check the appropriate column.

Property

/ Metal / Non-Metal
More than 4 valence electrons / X
Only forms positive ions / X
Covalent bonding / X
Gives away electrons in chemical reactions / X
Prefers to receive electrons in chemical reactions / X
Conducts electricity/heat / X
  1. For each of the following compounds, show how they are formed by either ionic OR covalent bonding.

*Diagrams are not shown here, however, a description of what you should have done is given next to each question. Refer to your notes and assignments/homework to see the difference between arrow diagrams (giving/taking electrons) and share diagrams.

  1. Potassium Fluoride (IONIC – use arrows to show electrons moving from potassium to fluorine)
  2. Carbon Dioxide (COVALENT – use share diagrams to show electrons being shared between carbon and each oxygen)
  3. Oxygen (COVALENT – sharing 2 pairs of electrons, resulting in a double bond)

d.  Beryllium Phosphide (IONIC – use arrows to show electrons moving from beryllium to phosphorous)

  1. Physical vs. Chemical
  2. How do you know if a chemical change has occurred? What about a physical change?

A chemical change has occurred if bubbling/fizzing is observed, if there is an unexplainable colour change or odour, if heat/light is produced, if a new substance is formed, if a precipitate is formed, if the reactant disappears, etc. A physical change usually involves a change in state. Examples include if a substance melts, freezes, evaporates, condenses or sublimes.

  1. While you take a shower, a cloud of steam fills the room. What type of change is this? Why?

This is a physical change. The water that you shower with is a liquid, but if the shower is hot enough, some of the water begins to evaporate, which causes steam to form. This is simply a change in state.

  1. You have some water and a pink solid. Out of curiosity, you mix the two together to see what happens. The pink solid simply dissolves into the water, making the water slightly pink, but still clear. What type of change is this? Why?

This is also a physical change. Even though there is a colour change, it is EXPLAINABLE. That is, you add a pink solid that just dissolves in the water. Dissolving or solubility is a physical property.

  1. Draw the shell diagram for argon. Include all of the sub-atomic particles in their appropriate locations. Why is argon so stable?

The shell diagram will not be drawn here, but you should know that Argon would have 18 protons and neutrons in its nucleus. It will have 3 electron shells, with 2, 8, and 8 electrons in the first, second and third shells, respectively. It stable because it has a full valence shell.

  1. What is the charge of the cations in the following compounds?
  2. Cu2S Cu+
  3. NiCl2 Ni+2
  1. Use the periodic table to complete the table below.
Element or Ion / Atomic Number / Mass Number / Charge / Protrons / Neutrons / Electrons / Group Number / Period Number / Family Name
23
11Na+1 / 11 / 23 / +1 / 11 / 12 / 10 / 1 / 3 / Alkali Metals
Ag
/ 47 / 94 / 0 / 47 / 47 / 47 / 11 / 4 / N/A
Be2+
/ 4 / 8 / +2 / 4 / 4 / 2 / 2 / 2 / Alkaline Earth Metals
1
1H / 1 / 1 / 0 / 1 / 0 / 1 / 1 / 1 / Alkali Metals
2
1H / 1 / 2 / 0 / 1 / 1 / 1 / 1 / 1 / Alkali Metals
  1. Write the formula for each compound.
  2. Potassium nitride K3N h. Nickel (III) Fluoride NiF3
  3. Zinc phosphate Zn3(PO4)2 i. Lithium iodide LiI
  4. Dinitrogen monoxide N2O j. Nitrogen dioxide NO2
  5. Lead (II) bromide PbBr2 k. Nickel (III) sulfite Ni2(SO3)3
  6. Dinitrogen pentoxide N2O5 l. Barium chloride BaCl2
  7. Calcium fluoride CaF2 m. Copper (II) oxide CuO
  8. Iron (II) sulfide FeS n. ammonium sulfide (NH4)2S
  1. Write the name for each compound.
  2. PbO2 Lead (IV) Oxide
  3. MgO Magnesium Oxide
  4. XeCl4 Xenon Tetrafluoride
  5. NiCl3 Nickel (III) Chloride
  6. (NH4)3N Ammonium Nitride
  7. Cu2S Copper (I) Sulfide
  8. CrCl2 Chromium (II) Chloride
  1. Use the following word equation to answer the questions that follow:

Calcium + Water à Calcium Hydroxide + Hydrogen Gas

  1. Write the chemical equation and balance it.

2Ca +2H2O à 2CaOH + H2

  1. How many calcium atoms are in the products? What about the reactants?

There are 2 calcium atoms in both the products and reactants! Remember, you can’t end up with MORE or LESS than what you started with!

  1. In ionic compounds, which ion is placed first, the anion or the cation?

The CATION (metal) always comes first – in both the name and chemical formula.

  1. Balance each of the following equations. Also, determine the REACTION TYPE.
  2. 2Ag + H2S à H2 + Ag2S SINGLE REPLACEMENT
  3. FeCl3 + 3 NaOH à Fe(OH)3 + 3NaCl DOUBLE REPLACEMENT
  4. C3H8 + 5O2 à 3CO2 + 4H2O COMBUSTION
  5. 8MgS à 8Mg + S8 DECOMPOSITION
  6. Mg3N2 + 6Li à 3Mg + 2Li3N SINGLE REPLACEMENT

Science 10 Chemistry In Class Review ANSWERS

1. True or False (correct the statement if false)

a) Metals usually react to form cations.

True

b) Strong bases have a high H+ concentration.

False: Strong bases have a high OH- concentration

c) Lithium and oxygen form a compound through covalent

bonding.

False: They form a compound through ionic bonding.

d) The maximum number of valence electrons for all

elements is 8.

False: Hydrogen and Helium only have 2.

e) When iron and oxygen combine, the formula is always

FeO.

False: Since iron is a transition metal, it has two possible charges (Fe+2 or Fe+3). So, two possible compounds are possible, depending on which cation is used: FeO or Fe2O3 are possible.

2. Fill in the Blanks

a) A phosphorous atom has 5 valence electrons.

b) A reaction that absorbs heat energy is described as

endothermic

c) An example of an anion with the same number of

electrons as argon is P-3, S-2 or Cl-1

d) When a base is dissolved in water, hydroxide ions

are produced.

e) Non-metals are poor conductors and tend to be

dull in appearance.

3. Short Answer

a) ---

b) Bonding not available. Formulas are given below:

i. Ca and N à Ca3N2

ii. Cl and Li à LiCl (the metal must come first!)

iii. H and P à PH3

c) Name the following compounds:

i. Fe2(SO4)3 iron (III) sulphate

ii. Pb(NO3)4 lead (IV) nitrate

iii. CaI2 calcium iodide

iv. Cr(NO3)3 chromium (III) nitrate

v. P2O5 diphosphorous pentaoxide

d) Write the formulas for the following compounds:

i. copper (I) nitrate CuNO3

ii. mercury (II) bromide HgBr2

iii. nickel (III) sulphide Ni2S3

iv. calcium hydrogen carbonate Ca(HCO3)2

v. nitrogen trichloride NCl3

e) Indicate the type of reaction and then balance. Also, write the word equations for each reaction.

i. 3H2SO4 + Al2O3 à Al2(SO4)3 + 3H2O

Double Replacement

“Hydrogen sulphate reacts with aluminum oxide to form aluminum sulphate and water.”

ii. C3H4 + 2H2 à C3H8

Synthesis

“Tricarbon tetrahydride reacts with hydrogen to form tricarbon octahydride.”

iii. 2NaCl + Pb(NO3)2 à 2NaNO3 + PbCl2

Double Replacement

“Sodium chloride reacts with lead (II) nitrate to form sodium nitrate and lead (II) chloride.”

iv. 4Al + 3O2 à 2Al2O3

Combustion

“Aluminum and oxygen combine to form aluminum oxide.”

v. Sn + 2AgNO3 à Sn(NO3)2 + 2Ag

Single Replacement

“Tin reacts with silver nitrate to form tin (II) nitrate and silver.”