Cumulative Exam Review Q-mew-lah-t’v

List of topics on the exam Periodic table elements 1 – 20 (you will receive a periodic table with your exam) Subatomic particles – proton, neutron, electron Energy levels Covalent bonds Ions and ionic bonds Types of reactions Experimental design Variables – Independent, dependent, controlled Organizing and graphing results of an experiment

Chemistry is the study of the composition, structure, and properties of matter. All matter is made of atoms. All atoms are made of: amu = atomic mass units. Always show units! Sub-atomic particle Charge Location Mass (amu) Proton 1.01 Neutron Electron 0.00054 Positive + Nucleus 🚫🚫 Neutral Nucleus Negative — Energy levels You can use the words to help you remember which goes with which! Electrons are way smaller than protons and neutrons

Reading the periodic table 1 Atomic number What does the atomic number tell you? The number of protons and electrons 1.01 Symbol The name of the element Li 3 Be 4 Atomic mass How heavy one atom of the element is 6.94 9.01 Na 11 Mg 12 22.98 24.30

Reading the periodic table Why does helium have 2, not 8 electrons in the outside energy level? Column 1 2 3 4 5 6 7 8 What does the column number tell us? The number of electrons in the outside energy level

+ + + + + + + + — — — 🚫🚫 🚫🚫 🚫🚫 🚫🚫 🚫🚫 🚫🚫 — — 🚫🚫 🚫🚫 — — — Assuming we can see all the particles in this nucleus, which element is this? — — Oxygen — How many electrons does this element have? 🚫🚫 🚫🚫 + 🚫🚫 Eight, the same number as protons 🚫🚫 + 🚫🚫 + + — 🚫🚫 — + What is the net charge of this atom? + + + 🚫🚫 🚫🚫 Neutral, because (+8) + (-8) = 0 — — —

Atoms are most stable when they have a full outside energy level — — — — How many electrons need to be added to make the outside ring full? 🚫🚫 🚫🚫 + 🚫🚫 🚫🚫 + 🚫🚫 + + 2. The capacity goes 2, 8, 8 — + 🚫🚫 — + + An ion is an atom with a different number of electrons and protons. What is the net charge of this ion? + 🚫🚫 🚫🚫 — — — -2, because +8 - 10 = -2 8 protons (positives) with 10 electrons (negatives) —

Sometimes, the easiest way to get a “full” energy level is to empty one. — How many electrons need to be added? How many removed? 🚫🚫 🚫🚫 + 6 added, 2 removed. It is easier to remove 2, so that is favoured. 🚫🚫 + — 🚫🚫 — + + What is the net charge of this beryllium ion? 🚫🚫 +2, because (+4) + (-2) = 0 4 protons (positives) with 2 electrons (negatives) —

Ionic charge quiz What is the net charge of an ion for each of the following atoms? 1. F 2. N 3. Ca 4. K 5. Ar 1. -1 2. -3 3. +2 4. +1 5. Argon already has a full outside energy level, it is does form ions! Answers:

Ionic bonds What happens when one molecule that adds electrons to form an ion meets a molecule that loses electrons to form an ion? No, thank you! Thank you! +2 -2 Mg O

Ionic bonds What happens when one molecule that adds electrons to form an ion meets a molecule that loses electrons to form an ion? The same thing that happens when a positive magnet meets a negative magnet: +2 -2 Mg O

Ionic bonds quiz How many of each atom are needed to form the following ionic compounds: 1. Potassium chloride – K x Cl y 2. Calcium oxide – Ca x O y 3. Magnesium chloride – Mg x Cl y 4. Potassium sulfide – K x S y 5. Aluminum Oxide – Al x O y 1. KCl 2. CaO 3. MgCl2 4. K2S 5. Al2O3 Answers:

Another way to make full energy levels is by covalent bonding Why are there 4 dots around the carbon? Why not 6 or 8? To make a molecule CHx, how many hydrogens are necessary? There are 4 electrons in the outside energy level of carbon. Hydrogen has one electron to offer, carbon needs 4 electrons, so 4 hydrogens. C H H H H

Another way to make full energy levels is by covalent bonding Any electron in a circle belongs to that atom. Carbon almost always forms covalent bonds. C H H H H

Covalent bonds quiz Draw the covalent bonds for the following molecules: 1. Hydrogen gas – H2 2. Dihydrogen monoxide – H2O 3. Ozone – O3 (hint: triangle) 4. Propane – CH3-CH2-CH3 5. Potassium hydroxide – KOH ← This one uses a covalent and an ionic bond!