Chemistry

Periodic Classification and Elements

1,176 Questions

Periodic classification organizes chemical elements based on atomic structure, periodic laws, and elemental properties. It covers historical classification systems, electron configurations, and periodic trends. Test takers preparing for chemistry sections will find these questions crucial for mastering fundamental element properties and atomic interactions.

Periodic table structureAtomic orbitalsElement identificationPeriodic laws

Periodic Classification and Elements Questions

Multiple choice

Which of the following is true about isobars?

  1. They occur at the same place in the periodic table.

  2. They have the same atomic mass.

  3. They have the same number of electrons.

  4. They are atoms of the same element.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

 They have the same atomic mass.

Multiple choice

Which is the lightest element in the universe?

  1. Helium

  2. Hydrogen

  3. Nitrogen

  4. Silicon
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Hydrogen is a chemical element. It is the simplest atom in the Universe. On a periodic table of the elements, hydrogen is on the top row, usually either on the left or on its own above the transition metals.

Multiple choice

The cause of periodicity is

  1. the increase in atomic number

  2. the increase in atomic mass

  3. the number of electrons in the valence shell

  4. the recurrence of similar outer most electronic configurations
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The cause of periodicity is the recurrence of similar outer most electronic configurations.

Multiple choice

Which of the following elements has the smallest size?

  1. C

  2. N

  3. O

  4. S
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Atomic size decreases on moving from lest to right along a row in the periodic table and it increases on moving from top to bottom  in a period.So oxygen has the smallest size of the given options.