Question

chapter 4 atomic structure
atomic number and mass number (page 110)

1. is the following sentence true or false? two atoms of the same element can have different numbers of protons.
2. the ____ number of an element equals the number of protons in an atom of that element.
3. is the following sentence true or false? two different elements can have the same atomic number.
4. the ____ number of an atom is the sum of the protons and neutrons in the nucleus of that atom.
5. complete the equation in the table below.

number of neutrons = mass number - ____
isotopes (page 112)
use the words in the box below to fill in the blanks in questions 10 - 12.
electrons neutrons isotopes protons

1. every atom of a given element has the same number of __ and __.
2. every atom of a given element does not have the same number of ____.
3. ____ are atoms of the same element that have different numbers of neutrons and different mass numbers.
4. all oxygen atoms have 8 protons. circle the letter of the number of neutrons in an atom of oxygen - 18.

a. 8
b. 10
c. 18

1. is the following sentence true or false? isotopes of oxygen have different chemical properties. ____

Explanation:

1. By definition, atoms of the same element have the same number of protons, so the statement is false.
2. The atomic number is the number of protons in an atom of an element.
3. Each element has a unique atomic number, so different elements cannot have the same atomic number, false.
4. The mass number of an atom is the sum of protons and neutrons in the nucleus.
5. Since Mass number = Number of protons + Number of neutrons, then Number of neutrons = Mass number - Number of protons.
6. Atoms of a given element have the same number of protons and electrons in a neutral state.
7. Atoms of a given element can have different numbers of neutrons (isotopes).
8. Isotopes are atoms of the same element with different numbers of neutrons and different mass - numbers.
9. For oxygen - 18, mass number = 18 and atomic number (number of protons) = 8. Number of neutrons=Mass number - Atomic number = 18 - 8=10.
10. Isotopes of an element have the same number of electrons and thus the same chemical properties, false.

Answer:

1. False
2. atomic
3. False
4. mass
5. Number of protons
6. protons, electrons
7. neutrons
8. Isotopes
9. b. 10
10. False