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Atom

Two major parts of atom? 1.Nucleus- contains protons and neutrons 2. Extra nuclear part- contains electrons

Draw of the atom.

Structure of Atom Nucleus Electron Shell or Orbit

Description of the Nucleus The nucleus is the central part of an atom. It is composed of protons and neutrons. The nucleus contains most of an atom's mass. It was discovered by Ernest Rutherford in 1911.

Description of Proton Proton is positively charged particle. It is found in the atomic nucleus. Protons were discovered by Ernest Rutherford.

Describe Neutron Neutron is uncharged particle. It is found in the atomic nucleus. Neutron was discovered by James Chadwick in 1932.

Describe Electron Electron is a negatively charged particle. Electron revolves around the nucleus in a definite circular path. Electrons was discovered by J. J. Thomson in 1897. Electrons determine properties of the atom. Chemical reactions involve sharing or exchanging electrons.

The structure of the atom ELECTRON – negative, Nigligible mass o.ooo555amu PROTON – positive, Mass 1.7825amu NEUTRON – neutral, mass-1.008665amu

The Hydrogen Atom Proton Electron Hydrogen has one proton, one electron and NO neutrons

The Helium Atom Proton Electron Neutron Helium has two electrons, two protons and two neutrons

The Lithium Atom Electrons Protons Neutrons

The Beryllium Atom Electrons Protons Neutrons Beryllium has four electrons, four protons and five neutrons.

The Boron Atom Electrons Protons Neutrons Boron has five electrons, five protons and six neutrons.

The Carbon Atom Electrons Protons Neutrons Carbon has six electrons, six protons and six neutrons.

The Nitrogen Atom Electrons Protons Neutrons Nitrogen has seven electrons, seven protons and seven neutrons.

The Oxygen Atom Electrons Protons Neutrons Oxygen has eight electrons, eight protons and eight neutrons.

The Fluorine Atom Electrons Protons Neutrons Fluorine has nine electrons, nine protons and ten neutrons.

The Neon Atom Electrons Protons Neutrons Neon has ten electrons, ten protons and ten neutrons.

The Sodium Atom Electrons Protons Neutrons Sodium has eleven electrons, eleven protons and twelve neutrons.

Atomic number (Z) Atomic number (Z): The number of protons in the nucleus which exactly balances the number of electrons in orbits. Atomic number(Z) = No.of protons = No.of electrons Atomic number = P = e-

Atomic Mass number (A) Atomic Mass number (A): The total number of protons and neutrons present in the nucleus of an atom. Atomic Mass number (A) = No.of protons + No.of neutrons Atomic Mass number (A) = P + N

Example 4 He 2 MASS NUMBER = number of protons + number of neutrons SYMBOL PROTON NUMBER = number of protons (obviously)

How many protons, neutrons and electrons? 1 11 16 H B O 1 5 8 23 35 238 Na Cl U 11 17 92

Electronic structure of Potassium K 19 39 Potassium has 19 electrons. These are arranged in shells… The inner shell has __ electrons The next shell has __ electrons The next shell has the remaining __ electron Electron structure = 2,8,8,1

How do shells fill? The first electron shell can only hold a maximum of two electrons. The second electron shell can hold a maximum of eight electrons. The third electron shell can also hold a maximum of eight electrons. The fourth electron shell can also hold eight electrons.

The First Twenty Elements Hydrogen 1,0,0,0 Helium 2,0,0,0 Lithium 2,1,0,0 Beryllium 2,2,0,0 Boron 2,3,0,0 Carbon 2,4,0,0 Nitrogen 2,5,0,0

First 20 Elements continued Oxygen 2,6,0,0 Fluorine 2,7,0,0 Neon 2,8,0,0 Sodium 2,8,1,0 Magnesium 2,8,2,0 Aluminium 2,8,3,0 Silicon 2,8,4,0

First 20 Elements continued Phosphorus 2,8,5,0 Sulphur 2,8,6,0 Chlorine 2,8,7,0 Argon 2,8,8,0 Potassium 2,8,8,1 Calcium 2,8,8,2

Describe Isotopes Atoms that have the same number of protons but different numbers of neutrons

Example of Isotopes of Hydrogen http://education.jlab.org/glossary/isotope.html

The Nobel gases The Nobel gases have full outer shells and they are found in group 0 of the periodic table. Helium, Neon, Argon, Krypton, Xenon and Radon.

For more detail contact us The Halogens Fluorine, Chlorine, Bromine and Iodine are the Halogens and they all have seven electrons in their outer shell. This is why they are found in group 7 of the periodic table. For more detail contact us