State Mendeleev’s periodic law

Newlands proposed the law of octaves .What is meant by the law of octaves?

Similar elements are placed in the same group in Mendeleev’s periodic table. This is a merit of this table.

Write two other merits of Mendeleev's periodic table

Name the scientist who proved by X- ray studies that properties of elements depend on atomic number instead of atomic mass?

(Mendeleev, Moseley, Newlands, Dobereiner)

The elements belonging to group 1,2 and group 13 up to 18 are known as ...........

( Transition metals, Representative elements, Noble gases, Lanthanoides )

* A, B and C are the three elements belonging to third period of the periodic table (symbols are not real)

* The element C belongs to 18^th group.

* When element B reacts with element A, B donates electrons to A.

a) Name the family to which 'C' belongs ?

b) Which element is metallic in nature?

c) Write down the given elements in the order as present in the periodic table.

In which name  the elements showing  both metallic and non-metallic nature  known as?

Give two example.

One of the triads of ‍Dobereiner is given below.

Analyse the table given above and write down any one characteristics of triads.

1. Choose the correct statement regarding modern periodic table

   i) It is based on the method adopted by Mendeleev .

   ii) Elements were arranged one the basis of atomic number.

   iii) Henry Mosely framed the modern periodic law.

   iv) Elements were arranged on the basis of atomic mass.

Find reason for the following

1. Size of atom decreases from left to right across a period.

2. Size of atom increases from top to bottom in a group.

A portion belonging to the same period of modern periodic table is given.

1. Which one of the given elements belongs to boron family?

2. Which element has 5 electrons in the outermost shell?

3. To which period do these elements belong?

4. What is the atomic number of noble gas in the given period?

 Bohr model of an element is given below.

IMAGE

1. Write the electronic configuration of the given element.

2. To which period and group does the element belong?

3. Write down the electronic configuration of the element just above the given element in the same group of the periodic table.

.Given below are the nuclear charges of certain elements belonging to second period of the periodic table.

IMAGE

a) Which is the biggest atom among the given elements?

b) Which is the smallest atom ?

c) Which atom has the highest ionisation energy?

d) Which atom has the lowest electro negativity?

Magnesium and Chlorine are two elements in the third period in the periodic table.

(Atomic number Mg -12 and Cl - 17)

a) Which one of them is electro positive in nature?

b) Which one is the electronegative element?

c) Which one of them has highest Ionisation energy? Why?

Choose the correct statements from the following and write them.

a) As the size of atom increases, the ionisation energy increases.

b) Electronegativity is high for smaller atom.

c) Metallic character increases as the size of atom increases

d) Size of atom increases on moving from left to right in a period.

A few elements are given below.

Write their electronic configurations find the pairs showing similarity in chemical properties.Give reason for your answer.

i) Write down the electronic configuration of the given elements.

ii) Find out the pair of elements which show similarity in chemical properties.

Give reason

A portion of periodic table is given

image

1. Write down the electronic configuration of the element P.
2. Find the atomic number of the last element in the same period to which N belongs.Justify your answer.
3. Write the electronic configuration of the first element in the same period to which the element Al belongs.

Find out the wrong statements.

1. As we move from top to bottom along a group, size of atom decreases.

2. On moving from left to right along a period, electronegativity increases .

3. As the size of atom increases, ionisation energy also increases.

4. Non-metals are found on the right hand side of the periodic table.

The given below is the electron dot diagram of the formation of NaCl from sodium and chlorine.

(Hint - sodium and chlorine belong to the same period in the periodic table.)

IMAGE

1. Which one of them has the largest atom?

2. Which one of them is a non-metal ?

3. Which one has higher electronegativity?

Match the data given in the columns A,B and C suitably.