An element X has a mass number = 37 and it contains 17 protons.

(i) Write the symbolic representation of the element.

(ii) Find the number of neutrons and electrons in the element.

(iii) Write the electronic configuration of the element.

An atom has an atomic mass of 7u. It has 2 electrons in K-shell and one electron in L-shell. How many neutrons does it have?

Lithium atom has an atomic mass of 6u and three protons in its nucleus. How many neutrons does it have?

The atomic number of Al and Cl are 13 and 17 respectively. What will be the number of electrons in Al^{3 +} and Cl^–?

Why are atomic masses of most of the elements are fractional and not whole numbers?

What are the number of protons, neutrons, and electrons in What are their atomic number and mass number?

Describe the Rutherford’s model of an atom. State one drawback of Rutherford’s model of the atom.

An ion M^2– contains 10 electrons and 10 neutrons. What are the atomic number and mass number of the element M? Name the element.

An atom of element E contains 3 protons, 3 electrons and 4 neutrons:

(a) What is its atomic number?

(b) What is its mass number?

(c) Write the electronic configuration of the element E.

(d) State whether element E is a metal or non-metal. Why?

(e) What type of ion, cation or anion, will be formed by an atom of element E? Why?

(f) Write the symbol of the ion formed by an atom of element E.

(g) What could element X be?

The atom of an element X has 7 electrons in its M shell

(a) Write the electronic configuration of element X.

(b) What is the atomic number of element X?

(c) Is it a metal or a non-metal?

(d) What type of ion will be formed by an atom of element X? Write the symbol of the ion formed.

(e) What could element X be?