Question

a) atomic mass c) number of neutrons b) atomic number d) volume 48. __ the subatomic particles in an atom are a) protons c) electrons b) neutrons d) all of the above 49. for two atoms to be of the same element they must have the same a) number of neutrons b) number of protons c) number of electrons d) mass 50. what happens when an atom in an excited state returns to the ground state? a) it gives off energy b) it becomes less stable c) it gains more energy d) it loses an electron 51. which of these statements are not true? a) atoms of the same element can have different masses. b) atoms of isotopes of an element have different numbers of protons. c) the nucleus of an atom has a positive charge. d) atoms are mostly empty space. 52. __ which of the following orbitals does not exist? a) 5f b) 3s c) 2d d) 6p

Explanation:

• 48: Atoms are composed of protons, neutrons, and electrons which are sub - atomic particles.
• 49: The atomic number, defined by the number of protons, determines the element. So, two atoms of the same element must have the same number of protons.
• 50: An excited - state atom is at a higher energy level. When it returns to the ground state, it gives off energy.
• 51: Isotopes of an element have the same number of protons but different numbers of neutrons. So, the statement that atoms of isotopes of an element have different numbers of protons is false.
• 52: The d - orbital starts from the 3rd energy level (n = 3). So, a 2d orbital does not exist.

Answer:

1. D) all of the above
2. B) number of protons
3. A) it gives off energy
4. B) Atoms of isotopes of an element have different numbers of protons.
5. C) 2d