January Exam Review
A- Simplified atomic model
P+ and n° in the nucleus. é on orbits with a 2-8-8-2 possibility.
1. Which of the following best represents the simplified atomic model of a potassium atom, K?
A) / / C) /B) / / D) /
B- Periodic trends
Properties followed from one period to the next.
Atomic radius (size) increases from ←↓
Reactivity in metals increases ←↓
Reactivity in non-metals increases →↑
Ionization and electro negativity increases from →↑
1. The graph below shows the electronegativity index of some elements of the periodic table.
Which of the following statement is true?
A) The electronegativity index steadily increases within the same family.
B) The electronegativity index steadily increases, then drops to 0 within the same period.
C) The electronegativity index remains constant within the same family period as one goes from left to right on the periodic table.
D) The electronegativity index steadily decreases within the same period.
2. Based on the graphs below, in general terms what happens to the atomic radius and ionization energy as the atomic number increases across a given period?
A)B)
C) C)
D) D) / As the atomic number increases, both the atomic radius and ionization energy generally increase.
As the atomic number increases, both the atomic radius and ionization energy generally decrease.
As the atomic number increases, the atomic radius generally increases and the ionization energy generally decreases.
As the atomic number increases, the atomic radius generally decreases and the ionization energy generally increases.
3. The graph below illustrates the atomic radius of certain elements as a function of their atomic numbers.
According to this graph, which statement best describes the change in the atomic radius as you move across a period?
A) The size of the atomic radius increases as you move from left to right across a period.
B) The size of the atomic radius decreases then increases across a period.
C) The size of the atomic radius decreases as you move from left to right across a period.
D) The size of the atomic radius increases and then decreases across a period.
4. The atomic size of an element is an example of a periodic property. The atomic size of the four elements below can be illustrated by using the atomic radius of each of these elements.
In which of the following periodic tables are these elements correctly placed?
A) / H / C) / H1 / 1 / 2 / 3 / 4
2
3
4
B) / 4 / D) / H
3 / 4 / 3 / 2 / 1
2
1
5. The following graph shows the ionization energies of certain elements as a function of their atomic numbers.
According to this graph, which of the following statements is TRUE?
A) Within a period, the ionization energy usually increases as the atomic number increases.
B) Within a period, the ionization energy usually decreases as the atomic number increases.
C) In general, the ionization energy of the elements in Period 3 is greater than the ionization energy of the elements in Period 2.
D) The ionization energy of the elements in Period 4 varies regularly when the atomic number increases regularly.
6. The following graph shows the atomic radius of certain elements as a function of their atomic number.
According to the graph, which of the following is the best description of the variation in atomic radius across a period?
A) The atomic radius increases from left to right.
B) The atomic radius decreases and then increases across a period.
C) The atomic radius decreases from left to right.
D) The atomic radius increases and then decreases across a period.
7. The graph below illustrates the atomic radius of certain elements as a function of their atomic numbers.
The following graphs illustrate various trends of the atoms on the periodic table.
I /II /
III /
Which graphs represent the trend for ionization energy and for atomic radius?
A) / Ionization energy - IAtomic radius - II
B) / Ionization energy - III
Atomic radius - II
C) / Ionization energy - II
Atomic radius - III
D) / Ionization energy - I
Atomic radius - III
C- Isotopes
An element with different number of neutrons, but the same number of protons (mass number will change)
1H1 1H2 1H3 proton number 1H3 → mass number
1. In general, in the periodic table, the atomic masses of elements increase as their atomic numbers increase. There are, however, exceptions to this rule. Which of the following accounts for these exceptions?
A) The number of electrons increases irregularly.
B) The number of particles in the nucleus increases regularly.
C) The number of neutrons increases irregularly.
D) The number of protons increases regularly.
2. Silicon comes as three different isotopes: Si 27, Si 28 and S1 29
a- For each form of silicon give the atomic number
b- For each form of silicon give the neutron number
c- Which form of Silicon is most abundant
D- Radioactivity
Three types of radioactive rays exist. The weakest is alpha which is stopped by paper and has a positive charge, beta is stopped by foil paper and is negatively charged and Gamma had no charge and is stopped by concrete.
1. The results of an experiment dealing with radioactivity are illustrated below.
What can you conclude from this experiment?
A) The atom consists of a nucleus and electrons.
B) The alpha and beta radiation is electrically charged.
C) The alpha and beta particles and the gamma rays have different masses.
D) The alpha, beta and gamma radiation is able to penetrate matter.
2. A radioactive source emits both beta, β, and gamma,g, radiation.
The radiation is focused into a beam and fired between two charged plates as shown in the diagram below.
What results would be expected?
A) b and g radiation would pass straight through the plates with no deflection.
B) b and g radiation would be deflected towards the negative plate.
C) Some radiation would be deflected towards the negative plate and some would pass straight through the plates.
D) Some radiation would be deflected towards the positive plate and some would pass straight through the plates.
3. The illustration at the right shows radiation from a radioactive point source passing through an electric field. /Which of the following correctly describes the rays formed after the radiation has passed through the electric field?
A) Ray 1 : negatively charged gamma (g) rays
Ray 2 : neutral alpha (a) particles
Ray 3 : positively charged beta (b) particles
B) Ray 1 : negatively charged beta (b) particles
Ray 2 : neutral gamma (g) rays
Ray 3 : positively charged alpha (a) particles
C) Ray 1 : positively charged beta (b) particles
Ray 2 : neutral gamma (g) ray
Ray 3 : negatively charged alpha (a) particles
D) Ray 1 : negatively charged alpha (a) particles
Ray 2 : neutral beta (b) particles
Ray 3 : positively charged gamma (g) rays
4. The diagram below illustrates three types of radiation directed between two electrically charged plates toward a screen.
What can be concluded from the results?
A) Only alpha radiation has an electric charge.
B) Only beta radiation has an electric charge.
C) Both alpha and beta radiation have electric charges.
D) Alpha, beta, and gamma radiation have electric charges.
E- Nucleus stability
The larger the nucleus more unstable it is because harder to make protons stop repelling themselves. All above 83 unstable
F- Half life
The time it takes a radioactive material to decay.
1. 15 g of uranium takes 35 000 years. Fill in the table to determine the percentage and amount left after 5 half lives have passed.
Gram / Decay time / Percent2. If you are using radioactive substances in your body for medical reasons. Would you want to use an isotope with a long or short half life? Why
3. If you are using radioactive substances to date an old bone. Would you want to use an iaotope with a short or long half life? Why
G- Nuclear fusion and fission
Nuclear fusion / Nuclear fissionDefinition / 2 small nuclei collide and form a heavier nucleus / Nucleus of the atom splits apart into lighter atoms
Fission 0n1 + 92u235 → 55Cs140 + 37Rb93 + 20n1
Fusion 1H2 + 1H2 → 2He3 + 0n1
H- Bonds
Ionic: metal donate electrons and non-metal accept electrons. Ions are formed.
Crossover rule- Write element symbols, give their valence, crossover the valence.
1. Crossover rule for molecular formula
Beryllium sulfideSodium oxide
Lewis diagram / Molecular formula / Name
Aluminum and fluorine
Lithium and phosphorus
Covalent: non-metal s share electrons with non-metals. Ions are not formed.
2. Molecular formula
Diphosphorus trisulfideCarbon tetrachloride
Lewis diagram / Molecular formula / Name
Phosphorus and chlorine
Hydrogen and oxygen
Chlorine
Oxygen
Polyatomic ions (radicals)
2 or more nonmetal atoms which act like ionic bonds and become charged
3. Mrs. Turriff and Mrs. Scandar have had enough of Robert the lab tech’s foul mood. They decided to sneak into the school in the middle of the night and mix all his chemicals. Surprisingly, some of the mixtures actually formed polyatomic ions while others did not mix since, they were incompatible. From the list of polyatomic ions below:
Charges: Nitrate: NO3- Sulphate: SO42- Phosphate: PO43- Hydroxide: OH-
Ca(NO3)2 K(SO4)2 AlPO4 Mg2OH
A- Determine which radicals are possible and which are impossible, justify your answer
B- Rewrite the correct radicals and correct the incorrect ones.
C- Name each radical.
4. Write the chemical formula for the compound formed between the anion PO43- and each of the following cations :
A) Sodium B) Calcium C) Aluminum
5. A compound is composed of hypothetical elements X and Y. X belongs to Family I A(1) and Y belongs to Family V A(15). What is the molecular formula of this compound?
6. Among the following chemical formulas, which contains two radicals (complex ions)?
A) H2SO4 B) NH4OH C) NaNO3 D) CaCO3
7. Which group of substances consists only of substances formed by covalent bonds?
A) K2O, PCl3, H2S C) CH4, CaS, NCl3
B) NaCl, MgO, AlF3 D) NH3, O2, P2O3
8. Which of the following molecular formulas represent ionic bonds?
1. LiCl 4. H2O 7. K2S
2. O2 5. AlCl3 8. N2O3
3. CH4 6. CaF2
A) 1, 5, 6 and 7 B) 1, 6, 7 and 8 C) 2, 3, 4 and 5 D) 2, 3, 4 and 8
9. Which of the following compounds have covalent bonds?
1. Na2CO3 5. Ca3N2
2. C3H8 6. P2O5
3. Al4C3 7. PBr5
4. Si3N4 8. Mg3P2
A) 1, 3, 5 and 8 B) 1, 3, 6 and 8 C) 2, 4, 5 and 7 D) 2, 4, 6 and 7
10. of the following statements correctly describe ionic bonds?
1. In reacting with water, potassium transfers an electron to produce potassium hydroxide, KOH.
2. In reacting with a metal, sulphur normally accepts two electrons.
3. Metals often form ionic bonds with one another.
4. Chlorine atoms share two electrons to form chlorine gas, Cl2.
5. H2O is an example of an ionic compound.
6. Copper oxide, CuO, is an example of an ionic compound.
A) 1, 2 and 4 B) 1, 2 and 6 C) 3, 4 and 5 D) 3, 5 and 6
11. Among the following chemical formulas, identify those substances formed as a result of covalent bonding.
1. CsF 2. PBr3 3. CaI2 4. BaAt2
5. SrO 6. S8 7. AlCl3 8. CO2
A) 2, 6 and 8 B) 1, 5 and 7 C) 2, 4 and 8 D) 3, 5 and 7
12. What is the correct molecular formula of a compound formed by an element "Y" from groupIVA(4) and an element "Z" from group VI A (16)? Give the correct molecular formula for this compound.
13. A compound is made of two hypothetical elements, X and Z. Element X belongs to familyIIA(2) and element Z belongs to family V A(15). Which of the formulas below correctly represents this compound?
A) X2Z3 B) X3Z2 C) X2Z5 D) X5Z2
14. A compound contains the elements X and Y. Element X belongs to Group I A (1). Element Y belongs to Group VI A (16). What is the molecular formula of this compound?
A) XY2 B) XY6 C) X2Y D) X6Y
15. Which of the following molecules is not consistent with the octet rule?
A) CF4 B) KO2 C) MgCl2 D) BaO
16. These elements combine to form compounds : Na, Ca, S, N, Al and Br. Which of the chemical formulas below respect the octet rule?
A) NaBr, Ca2S, Na2S B) N2S3, SBr, AlS C) NaBr, Al2S3, NBr3 D) AlS, Na2N, CaS
17. Based on their position in the Periodic Table, which two of the following elements can form three chemical bonds?
1. Sodium 2. Calcium 3. Aluminum
4. Chlorine 5. Phosphorus 6. Helium
A) 1 and 5 B) 2 and 4 C) 3 and 6 D) 3 and 5
18. Which of the following chemical formulas does not obey the rules of chemical nomenclature?
A) NH3 B) F2O C) H2O D) Cl2O
19. Four circular pieces of metal were brought close to one another during a laboratory experiment. Only one of these pieces of metal is a magnet.
Combination / AttractionYes / No
Piece 1 with piece 2 / ü
Piece 1 with piece 3 / ü
Piece 1 with piece 4 / ü
Piece 2 with piece 3 / ü
Piece 2 with piece 4 / ü
Piece 3 with piece 4 / ü
Which piece of metal is a magnet?
20. An electric current flows through a solenoid. Which diagram correctly illustrates the magnetic field produced by this solenoid?
21. A bar magnet is brought close to a current-bearing solenoid. In which one of the following situations will there be repulsion?
22. Which of the following diagrams correctly represents the magnetic lines of force between two solenoids?
A /B /
C /
D /
23. The current intensity is the same in each of the following electromagnets.