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Chemistry LibreTexts

General H002: Atomic structure

  • Page ID
    64166
  • The following questions relate to the atomic structure. These questions are for self-testing only, and are not suitable for assignments or exams.

    Express each value:

    1.The term nucleons refers to:

    A Protons
    B Neutrons
    C Electrons
    D Protons and neutrons
    E Protons, neutrons and electrons

    2.A beryllium atom has 4 protons, 5 neutrons, and 4 electrons. What is the mass of this atom?

    A 4
    B 5
    C 8
    D 9
    E 13

    3.Which of the following has 25 protons and 31 neutrons?

    A 56Mn
    B 56Ga
    C 25Ga
    D 31Mn
    E 56Ba

    4.Why does chlorine have an atomic mass of 35.5, which is not a whole number?

    A Chlorine contains an extra electron which makes it weigh more than 35.
    B Chlorine contains 17 protons and 18.5 neutrons.
    C Chlorine normally exists in an excited state, and so it weighs more than 35.
    D The chlorine was not pure when its atomic mass was measured.
    E Chlorine, as found in nature, contains a mixture of the isotopes 35Cl and 37Cl, in such proportions as to give an average atomic mass of 35.5

    5.Which of the following are isotopes?

    A 40K and 39K
    B 40K and 40Ca
    C 40K and 41Ca
    D 23Na and 39K
    E 23Na and 23Na+

    6.The halogens (group 7A, or group 17, of the periodic table) all have similar chemical properties (for example, forming singly charged negative ions). What aspect of their electron configurations leads to these elements having such similarities?

    A They all have a complete 1s2 shell at the lowest energy level.
    B They all have an identical Ns2Np5 configuration for their valence electrons (N is any whole number).
    C They all have p electrons in their outermost shell.
    D They all have an odd number of protons.
    E They all have an even number of neutrons.

    7.When an atom is neutral, this mean:

    A There are equal numbers of electrons and positrons orbiting in the electron shells.
    B The electrons present have zero charge.
    C The nucleus consists only of neutrons.
    D The number of electrons is equal to the number of protons.
    The atom in question has gained electrons from an outside source.

    8.Which of the following is correct?

    A An ion becomes negative when a proton is removed.
    B An ion becomes positive when electrons are removed and negative when electrons are added.
    C An ion becomes positive when an extra proton is added.
    D An ion becomes positive when positrons are added and negative when electrons are added.
    E An ion's charge is independent on the number of electrons present.

    9.An isotope of an element:

    A Contains the same number of protons, but the number of neutrons is changed.
    B Contains the same number of neutrons, but the number of protons is changed.
    C Contains the same number of protons and neutrons, but the number of electrons is changed.
    D Contains the same number of protons, but electrons are added onto the nucleus.
    E Contains the same number of protons and neutrons, and is simply charged by a radioactive element such as uranium.

    10.A neutral isotope of boron has an atomic number of 5 and atomic mass of 11. This isotope has:

    A 5 protons, 6 electrons, 6 neutrons
    B 5 protons, 5 electrons, 5 neutrons
    C 6 protons, 6 electrons, 5 neutrons
    D 6 protons, 5 electrons, 5 neutrons
    E 5 protons, 5 electrons, 6 neutrons

    Answers:

    1. D

    2. D

    3. A

    4. E

    5. A

    6. B

    7. D

    8. B

    9. A

    10. E