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 sets does not exist for 4p electron?

  1. n = 4, l = 1, m = - 1, ms = + 1/2

  2. n = 4, l = 1, m = - 3, ms = + 1/2

  3. n = 4, l = 1, m = - 2, ms = + 1/2

  4. n = 4, l = 1, m = - 2, ms = - 1/2

  5. n = 4, l = 1, m = 0, ms = - 1/2
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

For 4p electron, the four quantum numbers are given as: n = 4, l = 1, m = -1, 0, +1, ms = +1/2 or -1/2

Multiple choice

What is the Symbol of ' Iodine element'?

  1. I

  2. Io

  3. Id

  4. None of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Iodine is a chemical element with atomic number 53. Its symbol is 'I' (single letter), derived from its Greek name 'iodes' meaning violet-colored. Options like 'Io' or 'Id' are incorrect standard chemical symbols.

Multiple choice

According to the periodic law, when the elements are arranged in the _______________ order of their ________________, their properties show periodicity.

  1. increasing, atomic weights

  2. decreasing, atomic weights

  3. increasing, atomic numbers

  4. decreasing, atomic numbers

  5. increasing, atomic mass numbers
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

As per the definition of the modern periodic law stated by Mosely, the physical and chemical properties of elements are the periodic functions of their atomic numbers. Hence, the third option is correct.

Multiple choice

In the same period or group, there is a gradation in a particular property because

  1. there is a gradual increase in the number of shells across a period

  2. there is a gradual change in the electronic configuration of the elements

  3. there is a gradual increase in the number of valence electrons down the group

  4. there is a gradual increase in the atomic weights of the elements

  5. there is a gradual increase in their atomic size

Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

In the modern periodic table, the elements are arranged in the increasing order of their atomic numbers. The number of electrons in an atom are equal to its atomic number. Hence, there is a gradual change in their electronic configuration.

Multiple choice

Atomic numbers of four elements A, B, C, D and E are 14, 15, 17, 18 and 19, respectively. Which of these is highly non-metallic?

  1. A

  2. B

  3. C

  4. D

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

Metals have 1, 2 or 3 electrons in their outermost orbit and non-metals have 5, 6 or 7 electrons in their outermost orbit. The electronic configurations of A, B, C, D and E are 2, 8, 4; 2, 8, 5; 2, 8, 7; 2, 8, 8; and 2, 8, 8, 1, respectively. As the element C has 7 electrons in its outermost orbit as compared to 5 electrons in element B, so it is more non-metallic. Hence, option (3) is the correct answer.

Multiple choice

An element 'X' is a silver-gray solid with a density of 0.86 g/cm3 and melting point of 630C. The element exhibits vigorous reaction with cold water. In which group is the element likely to be found in the periodic table?

  1. Group 1

  2. Group 2

  3. Group 14

  4. Group 17

  5. Group 18
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Elements of group 1 are alkali metals. They are lustrous solids with low density and low melting points. They react vigorously with cold water to form alkalis. Hence, option (1) is the correct answer.

Multiple choice

An element 'A' is in group 2 of period 2 and another element 'B' is in the same group but in period 3. The proton number of 'A' is

  1. 1 less than that of 'B'

  2. 8 less than that of 'B'

  3. 8 more than that of ‘B’

  4. 7 less than that of 'B'

  5. 18 less than that of 'B'

Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

In the modern periodic table, the first period has 2 elements, the second has 8 elements and the third also has 8 elements. The electronic configuration of ‘A’ is 2, 2 and the electronic configuration of ‘B’ is 2, 8, 2. In a neutral atom, number of protons is equal to the number of electrons. Hence, ‘A’ will have 8 protons less than 'B'.