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 chemistry the periodic table dobereiner's triads development of the modern periodic table into the history

Fill in the blanks 
Zero group elements are known as _________.

  1. chalcogen

  2. inert gases

  3. halogens

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

The $'0'$ group elements have complete octate in outermost shell. As a result they have stable configuration due to which, they do not react with other elements. Hence they are known as inert gases.

Multiple choice chemistry the periodic table dobereiner's triads development of the modern periodic table into the history

An element $X$ belongs to fourth period and fifteenth group of the periodic table. Which of the following statements is true?

  1. It has a completely filled s-orbital and a partially filled d-orbital.

  2. It has completely filled s-and p-orbitals and a partially filled d-orbital.

  3. It has completely filled s-and p-orbitals and a half-filled d-orbital.

  4. It has a half-filled p-orbital and completely filled s-and d-orbitals.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
Group 15 has a valence shell electronic configuration of $ns^2np^5$ and period $=4$$ means its $n=4$

thus electronic configuration of element $X$  is $4s^24p^3$

Elements of Group 15 and period 2 onwards are: $N, P, As, Sb, Bi$

Thus $X$ is Arsenic ($As$) and has electronic configuration of: $1s^22s^22p^63s^23p^63d^{10}4s^24p^3$. 

Thus, $s$ and $d-$orbitals are fully-filled and $p-$orbital is half-filled.

Hence, the correct option is $\text{D}$
Multiple choice chemistry what is inside atom neutrons discovery of neutrons structure of atoms

The atoms of different elements having the same number of neutrons are known as :

  1. isobars

  2. isomers

  3. isotones

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

Two nuclides are isotones if they have same neutron number but different proton number e.g. $boron-12$ and $carbon-13$ both contain 7 neutrons so they are $isotones$.

Multiple choice chemistry study of the first element - hydrogen position of hydrogen in the periodic table hydrogen in periodic table trends in groups and periods

________ element has one electron in the outermost shell and attains duplet configuration after accepting one more electron and attains stability.

  1. Helium

  2. Hydrogen

  3. Lithium

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

Hydrogen has ${ 1e }^{ - }$ in outermost shell, in order to achieve stability either ${ e }^{ - }$ to be removed or added. When added it acquires a stable configuration forming duplet.

Multiple choice chemistry study of the first element - hydrogen position of hydrogen in the periodic table hydrogen in periodic table trends in groups and periods

Hydrogen is the ________ element on the earth.

  1. most abundant

  2. heaviest

  3. lightest

  4. none of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

$H$ is the lightest element on earth as there is only $1$ proton and ${ 1e }^{ - }$. All the other elements have more than 1 electrons and protons along with neutrons.

Multiple choice chemistry study of the first element - hydrogen position of hydrogen in the periodic table hydrogen in periodic table trends in groups and periods

The characteristics of hydrogen resemble the elements of__as well as__groups.

  1. IIA and VA

  2. IIIA and VIA

  3. IIA and VIA

  4. IA and VIIA
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Because hydrogen has ${ 1e }^{ - }$ in its outermost shell which is ready to be donated like that a group $1A$ (alkali metals). Also hydrogen can accept an ${ e }^{ - }$ to from ${ H }^{ - }$ having ${ 2e }^{ - }$ in outer shell which is stable this resembles to $VIIA$ group (Halogen family), as they also require only one ${ e }^{ - }$ to fulfill their incomplete octet.

Multiple choice chemistry study of the first element - hydrogen position of hydrogen in the periodic table hydrogen in periodic table trends in groups and periods

Hydrogen loses its electron to form $H^+$, in this respect, it resembles:

  1. halogens

  2. alkali metals

  3. transition element

  4. alkaline earth metals
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Alkali metals are electro positive in  nature it readily lose its valence shell electron, and hydrogen resembles like alkali metals.

Multiple choice chemistry study of the first element - hydrogen position of hydrogen in the periodic table hydrogen in periodic table trends in groups and periods

The usual valency of hydrogen is:

  1. $-2$
  2. $0$
  3. $+1 $ or sometimes $-1$
  4. $+2$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The electronic configuration of hydrogen is ${ 1s }^{ 1 }$ as it has only one electron in its single orbital. So, it can gain one or lose one electron from its s orbital, thereby, showing $+1$ or $-1$ valency.

Multiple choice chemistry study of the first element - hydrogen position of hydrogen in the periodic table hydrogen in periodic table trends in groups and periods

Which group hydrogen has resemblance?

  1. I-A

  2. II-A

  3. IV-A

  4. VII-A
Reveal answer Fill a bubble to check yourself
A,C,D Correct answer
Explanation

1.Resemblance of H with alkali metals-Both have one electron in its valency shell and form positive ion by losing electron.

2. Resemblance of H with IV group - Both have half filled valence shell. I.P. and E.A of both are comparable.
3. Resemblance of H with VII group- Both have one electron in valence shell and form anion by gaining electron.

Multiple choice chemistry study of the first element - hydrogen position of hydrogen in the periodic table hydrogen in periodic table trends in groups and periods

Hydrogen differs from elements of I-A group as:

  1. hydrogen is gas but others are solid at room temperature

  2. all are metals

  3. hydrogen is a non-metal but others are metal

  4. they donate one electron to become cation
Reveal answer Fill a bubble to check yourself
A,C Correct answer
Explanation

Group, I A are alkali metals while hydrogen is considered a nonmetal and hydrogen are in gaseous form while alkali metals are all solids at room temperature like sodium, potassium, etc.


So, the correct options are A and C