8th Grade Physical Science-Unit 2 study guide
Vocabulary
Protons
Neutrons
Electrons
Nucleus
Matter
Atom
Atomic number
Atomic mass
Mass Number
Ion
Isotope
Compound
Element
Heterogeneous mixture
Homogeneous mixture
Ionic bond
Covalent Bond
Practice questions
1. What kind of charge does the nucleus have?
The nucleus has a positive charge because it contains the protons (+) and the neutrons (no charge)
2. Where is most of the atoms mass located?
A majority of the mass is located in the nucleus where the protons and neutrons are found. The
protons and neutron are much larger than the electrons
3. What is the law of conservations of matter?
Matter cannot be created or be destroyed.
4. As fuel is burned in an airplane, it seems to disappear from the tank, suggesting that matter is
destroyed during the reaction. Explain why this is not true
According to the law of conservation of matter, it cannot be created nor destroyed. In this
example, the gas is merely changing states from a liquid to a gas.
5. Draw and label a carbon atom including; protons, neutrons and electrons.
6. How many protons does the atom have? 6
7. How many neutrons does the atom have? 6
8. How many electrons does the atom have? 6
9. What is the atomic number of the atom? 6
10. What is the mass number of the atom? 12
11. What is the number of valence electrons? 4
12. An atom with a neutral charge contains an equal number of ____Protons and Electrons_______.
13. The mass of the nucleus contains which two particles? Protons and neutrons
14. The following appears in a chemical equation:
2CO2
How many carbon atoms?____2_____
How many oxygen atoms?__4_____
15. Glucose (C6H12O6) is a kind of sugar molecule. How many total atoms are in a molecule of glucose? 24
16. Which elements would you predict to have the most similar physical and chemical properties to
Calcium? Atoms located in group 2 of the periodic table.
17. What number is most important in determining how an atom will bond? Valence electrons
18. What elements are most likely to form a compound with elements in row 2? Elements from group
16
19. Which group of elements has a full outer energy level containing eight electrons? Group 18, noble
gases
20. What is helium’s atomic number? 18
21. What is helium’s symbol? ___He______
22. What is helium’s atomic mass? ___4.003____
23. How many of the following subatomic particles does helium have?
Protons____2__
Neutrons___2______
Electrons___2______
24. Carbon has two three isotopes Carbon-12 and carbon-13 and carbon-14. For each of the isotopes,
complete the chart below. (10 points)
Isotope Name
Carbon-12
Carbon-13
Carbon-14
Atomic
number
6
6
6
Mass
number
12
13
14
Number of
Protons
6
6
6
Number of
Neutrons
6
7
8
Number of
electrons
6
6
6
25. Complete the chart using the periodic table provided to help you
Element
Iodine
Lead
Strontium
Hydrogen
Atomic
Symbol
Total number of
electrons
Number of
valence electrons
I
Pb
Sr
H
53
82
38
1
7
4
2
1
Number of
electrons lost or
gain
+(-1)
+/- (-4)
- (-2)
+/1 (-1)
Oxidation
Number
-1
+/1 (-4)
2
+/- 1