Question

identify the choice that best completes the statement or answers the question. bubble your selected answer carefully on your answer sheet.

1. isotopes of the same element have different

a. positions on the periodic table.
b. chemical behavior.
c. atomic numbers.
d. mass numbers.

1. an atom is considered to be

eutral\ because
a. it has neutrons.
b. nuclear forces stabilize the charges.
c. the numbers of protons and electrons are equal.
d. the numbers of protons and neutrons are equal.

1. what does the number 84 in the name krypton - 84 represent?

a. the atomic number
b. the mass number
c. the sum of the protons and electrons
d. twice the number of protons

1. the smallest particle of an element that retains the properties of that element is a(n)

a. atom
b. electron
c. proton
d. neutron

1. how many protons, electrons, and neutrons does an atom with atomic number 50 and mass number 125 contain?

a. 50 protons, 50 electrons, 75 neutrons
b. 75 electrons, 50 protons, 50 neutrons
c. 120 neutrons, 50 protons, 75 electrons
d. 70 neutrons, 75 protons, 50 electrons

1. carbon - 14 (atomic number 6), the radioactive nuclide used in dating fossils, has

a. 6 neutrons.
b. 8 neutrons.
c. 10 neutrons.
d. 14 neutrons.

Explanation:

1. Isotopes of the same element have the same atomic number (so they are in the same position on the periodic table and have similar chemical behavior). The difference lies in the number of neutrons, which affects the mass number.
2. An atom is neutral because the number of positively - charged protons is equal to the number of negatively - charged electrons. Neutrons are neutral, and nuclear forces are about holding the nucleus together, not about the atom's overall charge.
3. In the notation like Krypton - 84, the number represents the mass number. The atomic number is a fixed property of the element (for Krypton, it is 36). The sum of protons and electrons is not relevant here, and it is not twice the number of protons.
4. The atom is the smallest particle of an element that retains the properties of that element. Electrons, protons, and neutrons are sub - atomic particles and do not retain the element's properties on their own.
5. The atomic number is equal to the number of protons and, in a neutral atom, the number of electrons. The number of neutrons is calculated as mass number - atomic number. So, for atomic number 50 (protons = 50, electrons = 50) and mass number 125, neutrons = 125 - 50=75.
6. For Carbon - 14 with atomic number 6 (number of protons = 6), the number of neutrons is mass number - atomic number. So, neutrons = 14 - 6 = 8.

Answer:

1. d. mass numbers.
2. c. the numbers of protons and electrons are equal.
3. b. the mass number.
4. a. atom.
5. a. 50 protons, 50 electrons, 75 neutrons.
6. b. 8 neutrons.