Electron cloud Nucleus consisting of protons and neutrons

Electron cloud Nucleus consisting of protons and neutrons

Electron: It carries a negative charge. It has a mass only about 1/1850 of the proton. It is orbiting the nucleus at high speeds. Proton: It is found in the nucleus. It carries a positive charge. Electron cloud Nucleus consisting of protons and neutrons

Neutron: It does not carry any charge. It has about the same mass as a proton. Electron cloud Nucleus consisting of protons and neutrons

Atoms of different elements have different number of protons, electrons and neutrons. Example:

The atomic number is the number of protons in an atom.

Mass number: It is the total number of protons and neutrons in the nucleus of an atom.

For any neutral atom, the number of electrons is equal to the number of protons.

Data for atoms of the first 20 elements

Draw a labelled diagram to show the structure of an atom. Electron cloud Nucleus consisting of protons and neutrons

What is the charge of electron? Electron: It carries a negative charge. What is the charge of proton? It carries a positive charge. Compare the mass of electron and that of proton. Electron has a mass only about 1/1850 of the proton. Describe the movement of electron in an atom. It is orbiting the nucleus at high speeds.

What is the charge of a neutron? Neutron: It does not carry any charge. Compare the mass of neutron and that of proton. They have about the same mass. How do you know atomic number of an atom from the number of protons? The atomic number is the number of protons in an atom.

1. Complete the following table.

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2. Complete the following table for three element A, B and C

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3. Complete the following table.

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It is the distribution of electrons in the various shells of an atom. 4 th shell (energy level) 3 rd shell nucleus 2 nd shell 1 st shell (energy level)

Energy of the electron in the first shell is lower nucleus

Energy of the electron in the third shell is higher nucleus

The first shell can hold a maximum of 2 electrons

The second shell can hold a maximum of 8 electrons

The third shell can hold a maximum of 18 electrons

The following rules can be applied to find out the electronic configuration of an atom. The first 2 electrons go into the first shell and complete it. The next 8 electrons go into the second shell and complete it. The next 8 electrons go into the third shell. The next 2 electrons go into the fourth shell. The next 10 electrons go into the third shell and complete it.

Electron diagrams also show the distribution of electrons in atoms. For example, hydrogen atom E. C. : 1

Lithium atom, atomic no. = 3 E. C. : 2, 1

Sodium atom, atomic no. = 11 E. C. : 2, 8, 1

Calcium atom, atomic no. = 20 E. C. : 2, 8, 8, 2

Work out electronic configuration and electron diagram for beryllium, atomic no. =4 Beryllium atom E. C. : 2, 2

Work out electronic configuration and electron diagram for fluorine atom, atomic no. =9 E. C. : 2, 7

Work out electronic configuration and electron diagram for aluminium, atomic no. =13 E. C. : 2, 8, 3

Potassium atom, atomic no. = 19 E. C. : 2, 8, 8, 1

mass number atomic number

mass number atomic number

mass number atomic number

3. 5 Isotopes are atoms of a particular element with the same number of protons and electrons but a different number of neutrons. Three isotopes of hydrogen. 1 1 H 2 1 H 3 1 H

3. 5 Isotopes of an elements have the same number of electrons, therefore the same electronic configuration. They have different mass numbers. Two isotopes of chlorine 35 17 Cl 37 17 Cl

Which of the following are isotopes of the same element? Explain. A, C are isotopes of an element. B, D are isotopes of another element. Atoms A and atom C have the same number of protons but of different number of neutrons.