Periodic Classification of Elements Science - Periodic Classification of Elements

The element which forms a basis oxide has the atomic number of:

Which of the following is the valence shell for the elements of second period of the modern periodic table?

An element which is an essential constituent of all organic compounds belongs to following group of modern periodic table.

The three imaginary elements X, Y and Z represent a Dobernener's triad. If the atomic mass of element X is 14 and that of element Y is 46, then the atomic mass of element Z will be:

Which one of the following does not increase while moving down the group of the periodic table?

1. Atomic radius.
2. Metallic character.
3. Valence electrons.
4. Shells in the atoms.

Which of the following statements is not a correct statements about the trends when going from left to right across the periods of the periodic table?

1. The elements become less metallic in nature.
2. The number of valence electrons increases.
3. The atoms lose their electrons more easily.
4. The oxides become more acidic.

Which of the following statement is correct in regard to the classification of elements?

1. Elements in modern periodic table are arranged on the basis of increasing atomic masses.
2. Elements in Mendeleev's periodic table are arranged on the basis of increasing atomic numbers.
3. In modern periodic table, the element nickel of lower atomic mass is kept before the element cobalt of higher atomic mass.
4. In modern periodic table, the isotopes of chlorine having different atomic masses are kept in the same group.

Which of the following statement about the modern periodic table is correct?

1. It has 18 horizontal rows known as periods.
2. It has 7 vertical columns known as periods.
3. It has 18 vertical columns known as groups.
4. It has 7 horizontal rows known as groups.

Which of the following set of elements is written correctly in the order of their increasing metallic character?

1. Mg, Al, Si.
2. C, O, N.
3. Na, Li, K.
4. Be, Mg, Ca.

Fill in the following blanks with suitable words:
Group 17 elements are known as ________.

Fill in the blanks in the following statements:
The horizontal rows in a periodic table are called _________.

Fill in the following blanks with suitable words:
Group 18 elements are called _________.

Fill in the blanks in the following statements:
The tendency to gain an electron ________ on moving down in a group of the periodic table.

Fill in the blanks in the following statements:
In going across a period (right to left) in periodic table, the atomic size of the atom _________.

Fill in the following blanks with suitable words:
The horizontal rows in a periodic table are called ________.

Fill in the following blanks with suitable words:
The basis for modern periodic table is _______.

Fill in the following blanks with suitable words:
Group 1 elements are called ________.

Fill in the following blanks with suitable words:
Group 18 elements are called _________.

Fill in the following blanks with suitable words:
Group 17 elements are known as ________.

What property do all the elements in the same group of the periodic table as fluorine have in common?

Besides gallium, which two other elements have since been discovered for which Mendeleev had left gaps in his periodic table?

What is the number of valence electrons in the atoms of first element in a period?

Which group of elements was missing from Mendeleev’s original periodic table?

Name the scientists who gave the following laws in the early classification of elements:

1. Law of octaves.
2. Law of triads.

X and Y are the two elements having similar properties which obey Newlands’ law of octaves. How many elements are there in - between X and Y?

Which group of elements was missing from Mendeleev’s original periodic table?

What was the Mendeleev’s basis for the classification of elements?

What property do all the elements in the same group of the periodic table as fluorine have in common?

What property do all elements in the same column of the periodic table as boron have in common?

What names were given by Mendeleev to the then undiscovered elements.

1. Scandium.
2. Gallium, and
3. Germanium?

From the standpoint of atomic structure, what determines which element will be the first and which the last in a period of the periodic table?

State how the valency of elements varies.

1. In a group.
2. In a period, of the periodic table.

The elements A, B and C belong to groups 1, 14 and 17 respectively of the periodic table.

1. Which two elements will form a covalent compound?
2. Which two elements will form an ionic compound?

An element A has an atomic number of 6. Another element B has 17 electrons in its one neutral atom.

1. N which groups of the periodic table would you expect to find these elements?
2. What type of bond is formed between A and B?
3. Suggest a formula of the compound formed between A and B.

Would you place the two isotopes of chlorine, Cl - 35 and Cl - 37 in different slots because of their different atomic masses or in the same slot because their chemical properties are the same? Justify your answer.

Why do we classify elements?

Why did Mendeleev leave some gaps in his periodic table?

Which group of elements could be placed in Mendeleev’s periodic table later on, without disturbing the original order? Give reason.

Where should hydrogen be placed in the modern periodic table? Give reason for your answer.

What were the limitations of Newlands’ law of octaves?

How does the tendency to lose electrons change as we go down in group 1 of the periodic table? Why does it change this way?

Give two examples each of:

1. Group 1 elements.
2. Group 17 elements.
3. Group 18 elements.

The atomic masses of three elements X, Y and Z having similar chemical properties are 7, 23 and 39 respectively.

1. Calculate the average atomic mass of elements X and Z.
2. How does the average atomic mass of elements X and Z compare with the atomic mass of element Y?
3. Which law of classification of elements is illustrated by this example?
4. What could the elements X, Y and Z be?
5. Give another example of a set of elements which can be classified according to this law.

Why could no fixed position be given to hydrogen in Mendeleev’s periodic table?

Why does the size of the atoms progressively become smaller when we move from sodium (Na) to chlorine (Cl) in the third period of the periodic table?

Why do elements in the same group show similar properties but the elements in different groups show different properties?

Why could no fixed position be given to hydrogen in Mendeleev’s periodic table?

What were the limitations of Newlands’ law of octaves?

What were the limitations of Dobereiner’s classification of elements?

What are the merits of the modern periodic table of elements?

Can the following groups of elements be classified as Dobereiner's triads?

1. Na, Si, Cl.
2. Be, Mg, Ca.

Give reason for your answer.

(Atomic masses: Be 9; Na 23; Mg 24; Si 28; Cl 35. 5; Ca 40)

The following diagram shows a part of the periodic table in which the elements are arranged according to their atomic numbers.
(The letters given here are not the chemical symbols of the elements):

a 3	b 4		c 5	d 6	e 7	f 8	g 9	h 10
i 11	j 12		k 13	l 14	m 15	n 16	o 17	p 18

1. Which element has a bigger atom, a or f?
2. Which element has a higher valency, k or o?
3. Which element is more metallic, i or k?
4. Which element is more non-metallic, d or g?
5. Select a letter which represents a metal of valency 2.
6. Select a letter which represents a non-metal of valency 2.

Mendeleev predicted the existence of certain elements not known at that time and named two of them as eka - aluminium, and eka - silicon.

1. Name the element which has taken the place of (i) eka - aluminium, and (ii) eka - silicon.
2. Mention the period/ periods of these elements in the modern periodic table.
3. Write the group/ groups of these elements in the modern periodic table.
4. Classify these elements as metals, non - metals or metalloids.
5. How many valence electrons are present in the atoms of each of these elements?​​​​​​

Write the names and symbols of two very reactive metals belonging to group 1 of the periodic table. Explain by drawing electronic structure, how either one of the two metals reacts with a halogen. With which name is the bond formed between these elements known and what is the class of the compound so formed known? State any four physical properties of such compounds.

Which element has:

1. Two shells, both of which are completely filled with electrons?
2. The electronic configuration 2, 8, 2?
3. A total of three shells, with four electrons in its valence shell?
4. A total of two shells, with three electrons in its valence shell?
5. Twice as many electrons in its second shell as its first shell?

What are the merits of the modern periodic table of elements?

What are the advantages of the periodic table?

The following diagram shows a part of the periodic table in which the elements are arranged according to their atomic numbers.
(The letters given here are not the chemical symbols of the elements):

a 3	b 4		c 5	d 6	e 7	f 8	g 9	h 10
i 11	j 12		k 13	l 14	m 15	n 16	o 17	p 18

1. Which element has a bigger atom, a or f?
2. Which element has a higher valency, k or o?
3. Which element is more metallic, i or k?
4. Which element is more non-metallic, d or g?
5. Select a letter which represents a metal of valency 2.
6. Select a letter which represents a non-metal of valency 2.