Question

A student looks up an element on the periodic table. The table says that the atomic number of the element is 12 and the mass number of the element is 40. What information do these two numbers convey about the element? (1 point)
• The element has 40 protons and 12 neutrons
• The element has 12 protons and 12 neutrons
• The element has 12 protons and has 28 neutrons
• The element has 28 protons and 40 neutrons
In order for an atom to be considered "neutral"
', which of the following must be true?
(1 point)
• There are more protons than electrons
• The number of protons and electrons must be the same
• The number of protons and neutrons must be the same
• There are more neutrons than protons
In all elements in a group, the thing that is the same is the: (1 point)
• Number of protons
Number of electrons
•Number of electrons in the valence shell
• Number of neutrons

Answer 1

1) The element has 12 protons and has 28 neutrons.
- Atomic number = protons (12). Mass number = protons + neutrons (40), so neutrons = 40 − 12 = 28.

2) The number of protons and electrons must be the same.
- A neutral atom has equal positive (protons) and negative (electrons) charges.

3) Number of electrons in the valence shell.
- Elements in a group share the same number of valence electrons, giving similar chemical behavior.