G1oChem learner choice p.1f

Noble kagcs (or) Inert gases

Atom
'Atoni is a stnallcst particles of an element: It Contains three main, fnndatnentnl particles called proton. Cleetron and neutron.

1. Fupdamcnta particles of atoms
   Atoms a e made up of! three main fundatnental particles falled prOtons, neutrons and electrons;
   3.. Nucleus of atom
   : • Nucleus is;the stnall, heavy Ånd positively charged centre of atom that contains prötons and neutrons.
2. Proton
   Proton is a positively charged particle of atom. It. residys in the oucleus of atom. :
   Electron
   Electron is a negatively charged particle movingoutside and around the nucleus in the
   , circular orbit.'
   Atomic number
   'l'he nutnber of protons in the nucleus of an atom of an elemenüs known as the atomic number that eleJnei1t.
   Mass number
   [he masSnumber of an element is the sum of the number of protons and neutrons in the nucleus of an atom of that element
4. Isotopes
   Atoms of the sallie elemeni With differe t masses are called isotopes.
   Electropositive elements
   Metals are electropositive elements. They tend to lose electrons and fonn positive ions 10, Electronegative elements
   Non-metals are electronegative elements. They tend to gain electrons and form negati9e ions.
   Noble gases are neither electropositive n, electronegative. '[hey have little tendency gain or lose electrons.
5. Metalloids
   Metalloids show both properties d metal ar non-metal. They are along the dark line of period ic table.
6. Complete electronic structure
   'Ibe arrangement of all electrons of an aton of an element is sometimes called the Compleu
   -aectronic structure of that element.v
7. Essential electronic structure
   The arrangement of valencg electrons o an atom of an elenient is •sometimes callec the essential, eleqronic structure of thw element.
8. Alkaline, earth metals (According to thc position in the periodic •table)
   The elements in group IIA of the period table are alkaline earth metals. The essenti I electronic structure of those elements is ne
9. Valence
   The number or-zG6ms of element (i.e., Na or H or CI) that can combine with one atom of an element is known as the valence (combining capacity) Of that é.le—
10. Ionization Energy
    The energy required to remove an electrOn from a gaseous atom to form a gaseous iöliis called ionizatioo ener»•.
    Na(g) + energy —Y e
11. Electron affinity
    Electron affinity ofan element is the energ released when an elegtron is added to a gaseoy.• atom to form a gaseous ion.
    Cl (g) + e Cle (g) energv