Chem Bond
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project on chemistry...
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Chemistr y Holiday Chemistry Assignment Ass ignment Assignm ent Valencies and Atomic Bonds….
Atom – the smallest unit unit of matter “indivisible”
Atoms are the smallest particles which exist , atoms make up molecules molecules which in turn make up matter… But what are they called ‘protons’ ‘protons’ , ‘neutrons’ and they made up of ?? Sub-atomic particles called ‘electrons’ ! Protons are positively charged particles, electrons electrons are negatively charged particles and eutrons eutrons have no charge
toms ma"e up molecules by ‘Bonding’ # $lectrons are responsible as they are e%changed between atoms to form&
Atom – the smallest unit unit of matter “indivisible”
Atoms are the smallest particles which exist , atoms make up molecules molecules which in turn make up matter… But what are they called ‘protons’ ‘protons’ , ‘neutrons’ and they made up of ?? Sub-atomic particles called ‘electrons’ ! Protons are positively charged particles, electrons electrons are negatively charged particles and eutrons eutrons have no charge
toms ma"e up molecules by ‘Bonding’ # $lectrons are responsible as they are e%changed between atoms to form&
Electron Shs
a)
Atomic number = number of Electrons
b)
Electrons var in the amount of ener! the possess, and the occur at certain ener! levels or electron shells.
c)
Electron shells determine how an atom behaves when it encounters other atoms
Electros a ped in hs corig ules "he maximum number of electrons present in a shell is !iven b theformula #n$n , where n is the orbit number
"he maximum number of electrrons that can be accommodated in the outermost orbit is %
Electrons are not accommodated in a !iven shell,unless the inner shells are &lled in a step wise manner
'ctet (ule ) atoms tend to gain, lose or share electrons so as to have * electrons + would li"e to ain electrons would li"e to ain . electrons ' would li"e to ain / electrons
'h are electrons important( )
Elements have di*erent electron con&!urations
di*erent electron con&!urations mean di*erent levels of bondin!
"o form an octet in an atom electrons are exchan!ed and when an atom reaches it+s octet it is a molecule which forms matter which is reall useful to us
Electron Dot Structures Symbols of atoms with dots to represent the valence-shell electrons 1
2
13
14
15
16
1
1!
"
"e#
$i
%e
'a
*+
%
,l
&
Si
'
(
S
# )
#&l
#'e #
#,r #
Chemical bonds: bonds an attempt to fill electron shells
1./onic bonds 0 2.&ovalent bonds 0 3.*etallic bonds
/('/& %('D bond formed between two ions by the transfer of
)ormation of /ons from *etals
/onic compounds result when metals react with nonmetals
*etals lose electrons to match the number of valence electrons of their nearest noble +as
Positive ions form when the number of electrons are less than the number of protons
roup 1 metals
ion
roup 2 metals roup 13 metals
ion 2 ion 3
1
)ormation of Sodium /on Sodium atom
'a
0 e
2-!-1 11 p
Sodium ion
'a
2-! 'e 11 p
11 e-
1 e-
1
Some 7ypical /ons with ositive &har+es &ations roup 1
roup 2
"
*+2
$i
&a2
'a
Sr2
8
%a2
roup 13 ,l3
)ormation of *a+nesium /on *a+nesium atom
*+
0
2-!-2 12 p 12 e
*a+nesium ion
2e
*+2 2-!
'e
12 p 1 e2
/ons from 'onmetal /ons /n ionic compounds9 nonmetals in 159
169 and 1 +ain electrons from metals 'onmetal add electrons to achieve
the octet arran+ement 'onmetal ionic char+e#
3-9 2-9 or 1-
)luoride /on unpaired electron octet 1-
# ) 2- : p : e
e
# )# 2-! 'e : p 1 e1ionic char+e
/onic %ond
Between atoms of metals and nonmetals with ver di*erent electrone!ativit
Bond formed b transfer of electrons
roduce char!ed ions all states. -onductors and have hi!h meltin! point.
Examples /a-l, -a-l#, 0 #1
1). Ionic bond 0 electron from a is transferred to +l, this causes a charge imbalance in each atom# 1he a becomes 2a34 and the +l becomes 2+l-4, charged particles or ions#
&(;,$E'7 %('D bond formed by the sharing of electrons
-ovalent Bond
%etween nonmetallic elements of similar electrone+ativity.
)ormed by sharin+ electron pairs
Stable non-ioni (29 &(29 &2"69 "2(
%onds in polyatomic ions and diatomics are all in covalent bonds
NONPOLAR COVALENT BONDS
when electrons are shared equally H or Cl 2
2
2. Covalent bonds- 1wo atoms share one or more pairs of outer-shell electrons#
POLAR COVALENT BONDS
when electrons are shared but shared H O unequally 2
- water is a polar molecule because o%ygen is more electronegative than hydrogen, and therefore electrons are pulled closer to o%ygen#
*E7,$$/& %(' bond found in metals> holds metal atoms to+ether very stron+ly
*etallic %ond
2ormed between atoms of metallic elements
Electron cloud around atoms
3ood conductors at all states, lustrous, ver hi!h meltin! points
Examples /a, 2e, Al, Au, -o
/onic %ond9 , Sea of Electrons
*etals )orm ,lloys 5etals do not combine with metals# 1hey form lloys which is a solution of a metal in a metal# $%amples are steel, brass, bron6e and pewter#
"hank ou 444
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