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Three fundamental particles in an atom. Proton. Neutron. Electron. Proton. Symbol. p. Position in atom. Inside the nucleus. Relative Charge (compare with proton ). +1. Relative mass (compare with proton). 1. Actual mass. Neutron. Symbol. n. Inside the nucleus. Position in atom.
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Three fundamental particles in an atom Proton Neutron Electron
Proton Symbol p Position in atom Inside the nucleus Relative Charge (compare with proton ) +1 Relative mass (compare with proton) 1 Actual mass
Neutron Symbol n Inside the nucleus Position in atom Relative charge 0 Relative mass 1 Actual mass
Electron Symbol Position in atom moving around the nucleus Relative charge -1 Relative mass Actual mass
e e e e e Atomic structure - - - - - - - - electron n (s) p (s) - - - - - - - - - -- - - - - nucleus
12n 11p Symbol Atomic content of an atom no. of protons = 11 no. of electrons =11 no. of neutrons = 12
Atomic Content of • no. of protons =6 • no. of neutrons = 12 - 6 • = 6 • no. of electrons = 6 • (An atom is neutral in charge)
Atomic Content of : • no. of protons = 7 • no. of electrons = 7 • no. of neutrons= 14 – 7 • = 7
Atomic Content of • no. of protons = 6 • no. of neutrons= 14 – 6 • = 8 • no. of electrons = 6
mass number atomic number Mass number = no. of p + no. of n atomic number = no. of protons
Isotopes Name of element : carbon carbon No. of protons : 6 6 No. of neutrons : 86 No. of electrons : 6 6 Isotopes are atoms of same elements which have thesame atomic number but different mass number
Isotopes Burn in air Carbon dioxide Carbon dioxide Mass 14 units 12 units Radioactivity Give radiation Does not give radiation (stable)
8n 6p 7n 7p nucleus nucleus Extension : Isotopes ( For reference only ) A neutron in a nucleus of breaks into Electrons and energy are emitted to the surroundings Carbon -14 dating
Properties of isotopes • Same chemical properties • Different physical properties • e.g. mass • b.p. and m.p. • radioactivity
Or 12 Mass of 1 atom Standard reference : 1 is equivalent to Actual mass VS relative mass Which one is more convenience? Relative mass
Simplified rule : We regard Relative mass of 1p = 1 Relative mass of 1n = 1 Relative mass of 1e = very small = 0
Relative mass of isotopes 30 Relative mass 29 28 % abundance 3.1% 92% 4.7% Do the three isotopes have the same chemical properties? Yes
Relative atomic mass of isotopes It isdifficultand notnecessaryto separate the isotopes in most of the reactions. Average relative mass of silicon is used to denote the mass of a silicon atom.
Relative atomic mass of silicon ( P.5 e.g.1 ) Relative mass 28 29 30 % abundance 92% 3.1% 4.7% ( Relative ) Atomic Mass of silicon = 28 x 92% + 29 x 4.7% + 30 x 3.1% = 28.053 = 28.05
Ex1. Relative atomic mass of Chlorine Relative mass 35 37 % abundance 75.5% 24.5% Atomic mass of Chlorine = 35 x 75.5% + 37 x 24.5% = 35.5