Question

Which of the following is true about the MODERN periodic table?

a
As you go down a group the atomic mass decreases.
b
Elements are arranged in order of increasing atomic Mass
c
Elements with similar chemical properties and valence shell electron number are arranged in columns called periods.
d
Elements are arranged in periods based on the valence shell number

Answer 1

Correct answer: d

Explanation:
- The modern periodic table is arranged by increasing atomic number, and periods (rows) correspond to the principal energy level (valence shell) of the atoms — so statement d is true.
- a is false: atomic mass generally increases down a group.
- b is false: arrangement is by atomic number, not atomic mass.
- c is false: elements with similar chemical properties and the same number of valence electrons are in columns called groups (not periods).