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

The symbol of an element represents

  1. one atom of the element

  2. one molecule of the element

  3. all the atoms of the element

  4. all the molecules of the element
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The symbol of an element represents one atom of the element.

Multiple choice

Electrons in the outer orbit are

  1. nuclei

  2. waves

  3. valence

  4. holes

  5. shells
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Valence, also known as valency or valence number, is the number of valence bonds a given atom has formed or can form, with one or more atoms. For most elements the number of bonds can vary. Option 3 is correct.

Multiple choice

What is the determining factor for an element to be kept in a period?

  1. The number of shells in an atom of an element

  2. The number of electrons in outer shell of an atom of an element

  3. The number of protons and neutrons in the nucleus of an atom

  4. The number of neutrons in the nucleus of an atom
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The number of shells in an atom determines its period in periodic table. If an element has one shell, it is kept in first period and so on.

Multiple choice

Which of the following correctly defines the valency of an atom?

  1. The number of electrons in outer orbit of an atom

  2. The number of electrons in inner orbit of an atom

  3. The number of electrons, which an atom can donate, accept or share

  4. The number of shells present in an atom
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The valency of an atom is equal to the number of electrons, which an atom can donate, accept or share to attain the configuraton of inert elements.

Multiple choice

Mendeleev's periodic table does not help in ________________.

  1. systematic study of elements

  2. prediction of new elements

  3. correction of atomic masses

  4. position of isotopes
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The periodic table by Mendeleev could not explain the position of isotopes. It is because it is based upon the atomic masses of elements.