The periodic table consists of elements arranged according to their atomic numbers . In this sub topic , we will look at those element from atomic number 1 to 20 . Am sure almost every learner develops a way of identifying the elements in an order starting with the 1st to the 20th . HiContinue reading “The first 20 element in the periodic table”
Tag Archives: Structure of an atom and the Periodic table
Structure of an atom ⚛️
ATOMIC NUMBER AND ATOMIC MASS ( MASS NUMBER). – Atomic number: is the number of protons in the nucleus of an atom . Q. What is the atomic number of elements X with 5 electron in it’s energy levels ? Explain. -Element X has atomic number 5 , this is because it has 5e which equals the number of protons , therefore it has 5p which equals the atomic number. Atomic number= no. of protons= no. of electrons Mass Number ( Atomic mass ) : is the sum of the protons and neutrons in the nucleus of an atom. Mass number= protons (p) + neutrons (n) Q. An element Y has 8 protons , 8 electrons and 8 neutrons, find the mass number of the element Y. Mass number= p+ n = 8+8 = 16. Q. A Magnesium atom has atomic mass of 24 and atomic number 12 , how many neutrons are there in the magnesium atom ? Atomic number = p Atomic mass also known as mass number = p+n Therefore ; neutrons= atomic mass – no. of protons n = 24-12 n= 12. – Both mass number and atomic number can be written along with the symbol of an element. – Mass number is written as the superscript (above the symbol) while atomic number is written as a subscript ( below the symbol) to the left of the chemical symbol .
STRUCTURE OF AN ATOM AND THE PERIODIC TABLE . _Structure of an atom What is an atom ? An atom is the smallest particle of an element which can take part in a chemical reaction. – An atom has a diameter of 10–⁸ cm. ( 0.00000001) . – An atom is made up of three sub atomic particle; a) Protons b) Neutrons c) Electrons – The protons and neutrons are found inside the nucleus of an atom while electrons are found in the region around the nucleus ( in the shells or energy levels ) . – Protons are positively charged (+ve) while electrons are negatively charged (-ve) . The neutrons have no charge ( neutral particles ) . Why is an atom said to be electrically neutral ? In any given atom , the number of protons ( in the nucleus) equal to the number of electrons( in the shells ) p=e. Where p= protons e= electrons Why are protons and neutrons referred to as nucleons ? This is because both the protons and neutrons are found in the nucleus of an atom of an element.
✓ Lithium has three protons (3p) , three electrons (3e) and four neutrons (4n) and therefore it’s structure is ; Browse for more content
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