1. Timed Quiz
Answers.

2. 1 The number of valence electrons in Group 2 elements is — A 0 B 1 C 2 D 3
Group number in the Periodic Table tells you the number of valence electrons for all the elements in that group

3. 2. What happens to the number of electrons in an atom as the atomic number on the Periodic Table increases? A increases B decreases C remains the same D depends on the atom
Atomic number will tell you the number of protons and electrons in an atom of any element

4. 3. Which of the following describes the properties of noble gases
3. Which of the following describes the properties of noble gases? A They have high boiling points. B They are highly reactive. C They are generally unreactive. D They are solid at room temperature.
Noble gases (inert gases) are unreactive with other elements because they have a filled or complete outer shell

5. 4. Based on information from the periodic table, which two elements will bond in ratio similar to that of lithium oxide? (2:1) A magnesium and sulfur B sodium and fluorine C hydrogen and sulfur D magnesium and oxygen
Hydrogen has a 1+ oxidation number and sulfur has a 2+ oxidation number. When you “criss-cross” these numbers to form the compound, the ratio between both of them is 2:1 (H2S)

6. 5. From which of the following atoms would it be the MOST difficult to remove an electron? A sodium B aluminum C sulfur D chlorine
Chlorine has a high electronegativity and a small atomic radius (nucleus of Cl atoms pull all of its electrons closer to itself, thus requiring more energy to remove electrons from it)

7. 6. If you wanted to separate a mixture of isopropyl alcohol and water, which example below would help you select the technique you should use? A The boiling point is 82ºC. B The mixture is clear. C The water is tap water. D Eight oz of alcohol is added to 8 oz of water.
The different boiling points of water and this solution of alcohol and water can help you separate them since water will not boil until you reach 100 degrees.

8. 7. The properties of elements, according to periodic law, can be predicted by — A the number of isotopes B the solubility of the element C the position on the periodic table D the color of the element
Elements in the Periodic Table are arranged by their properties (which are periodic) and increasing atomic numbers

9. 8. Which family correctly represents the elements in Group 1 on the periodic table? A transition metals B alkali series C lanthanide elements D actinide series
Group 1 is known as the Alkali family

10. 9. How many electrons are in a Cd3+ ion? A 112 B 51 C 48 D45
Since this is an ion with a +3 charge, it means that it lost 3 electrons (hence the positive charge). Cd has a total of 48 electrons but since it lost 3, it now has 45.

11. 10. As the atomic number increases within a group of elements, the atomic radius usually : A decreases B remains the same as the one above it C increases D decreases, then increases
As atomic radius increases, more electrons and energy levels increase too. This means that it is much harder for the nucleus to hold all these electrons closer to it, thus the atomic radius increasing as well.

12. 11. How many neutrons would have? A 16 B 18 C 20 D 32
In an isotope, subtract the atomic number (bottom) from the mass number (top) to calculate the number of neutrons.

13. 12. An isotope of mercury has 80 protons and 120 neutrons
12. An isotope of mercury has 80 protons and 120 neutrons. What is the mass number of this isotope? A 80 B 120 C 200 D 201
Mass number of an isotope is the number of protons plus the number of neutrons.

14. 13. A sample of Element X is found to contain 72
13. A sample of Element X is found to contain 72.15% of isotope type 1 ( amu) and 27.85% of isotope type 2 ( amu). Calculate the average atomic mass.
A amu
B amu
C amu
D86.49 amu
Use the formula to calculate the average atomic mass of an atom of an element (using mass of isotopes and their percent abundances)

15. 14. Which of the following is TRUE about Nickel59
14. Which of the following is TRUE about Nickel59? A 28 neutrons B 28 protons C 31 electrons D 59 neutrons
This isotope has a mass number of 59 (neutrons + protons). The only true statement about his isotope is that it has 28 protons.

16. 15. As the wavelength of a wave increases, which is also TRUE
15. As the wavelength of a wave increases, which is also TRUE? A The energy of the wave will increase. B The speed of the wave will increase. C The frequency of the wave will decrease. D Planck's constant will decrease.
As the length of a wave increases (wavelength), less and less waves pass through a specific point in a certain amount of time (frequency). Thus frequency decreases.

17. 1. The cathode ray experiments led to which particle being discovered
1. The cathode ray experiments led to which particle being discovered? A nucleus B proton C neutron D electron
J.J. Thomson discovered the existence of the electron through a cathode ray experiment

18. 2. Which of the following statements is MOST accurate regarding atoms?
A Atoms only contain protons.
B Most atoms cannot combine with other atoms.
C Chemical reactions divide atoms into smaller units.
D Atoms of the same element may have different mass numbers.
Atoms of the same element have different masses because they can have different number of neutrons (isotopes)

19. 3. Why is an atom considered electrically neutral
3. Why is an atom considered electrically neutral? A neutrons equal the number of protons B proton forces pull on the neutrons C electrons equal the number of protons D electrons equal the number of neutrons
Number of positively charged particles (protons) is equal to number of negatively charged particles (electrons)

20. 4. Which of the following atoms would have the largest ionic radius
4. Which of the following atoms would have the largest ionic radius? A lithium B sodium C potassium D cesium
All of these atoms will lose one electron and become a positive ion and the atomic radius will be reduced. Cesium still will have the largest ionic radius simply because it still has more electrons than the other atoms and its radius will be larger than the others (harder for the nucleus to pull all the electrons towards it).

21. 5. A solution in which more solute is dissolved than is typically soluble at a given temperature is — A unsaturated B saturated C supersaturated D diluted
A supersaturated solution will have more than the maximum amount of solute dissolved in the solvent at a given temperature