Question

1. choose the best answer.

elements in a group have similar properties due to
neutrons
valence electrons
atomic number
protons

1. choose the best answer.

how do you determine the number of valence electrons an element has?
it is the same number as the period number.
it is the same number as the last digit of the group number.
it is the same as the atomic mass.
it is the same as the atomic number.

Explanation:

• For the first question: The chemical properties of elements are mainly determined by the number and arrangement of valence electrons. Elements in the same group have the same number of valence electrons, so they have similar chemical properties. Neutrons mainly affect the mass of the atom. The atomic number is the number of protons in the nucleus, which determines the type of element. Protons are related to the charge of the nucleus.
• For the second question: In the periodic table, for main - group elements (groups 1 - 2 and 13 - 18), the number of valence electrons is equal to the last digit of the group number. The period number is related to the number of electron shells. The atomic mass is the sum of protons and neutrons. The atomic number is the number of protons.

Answer:

1. valence electrons
2. It is the same number as the last digit of the group number.