General Chemistry
Faculty of Allied Medical Sciences
(MGGC-101)
Supervision:Prof.Dr.Shehata El-Sewedy
Dr.Fatma Ahmed
Chemical bonds &chemical reactions
Outcomes By the end of this lecture, the
students will be able to1-Understand the meaning of chemical bond
2-learn to type of chemical bond3-To differentiate between solute, solvent and
solution4-Recognize the meaning of electrolyte
5-To know types of chemical reactions6-To differentiate between acids and bases
Chemical bonds
CHEMICAL BONDS: THE OCTET RULE Why do atoms bond together? More stable (has less energy) Octet Rule
Atoms form bonds to produce the electron configuration of a noble gas
because the electronic configuration of noble gases is particularly ) stable)
For most atoms of interest this means achieving a valence shell
configuraon of 8 electrons corresponding to that of the nearest noble gas
Atoms close to helium achieve a valence shell configuraon of 2 electrons
Atoms can form either ionic or covalent bonds to satisfy the octet rule
How to describe bonding?
The ionic bond: formed by the transfer of one or more
electrons from one atom to another to create ions The covalent bond: results when atoms share
electrons Atoms without the electronic configuration of a noble gas
generally react to produce such a configuration
1 )Ionic Bonds
Results from transfer of electrons from one atom to another such as NaCl, NaBr and so on.
Na Na + e
Cl + e Cl
Na + Cl NaCl
ionic bond
Electronegativitymeasures the ability of an atom to attract electrons
Ionic Bonds: One Big Greedy Thief Dog!
Electronegativities of Some of Elements
The electronegativity increases across a
horizontal row of the periodic table from left to right
The electronegativity decreases go down a vertical column
F>O>N>C
fluorine is the most electronegative atom. Ionic substances, because of their strong internal electrostatic forces, are usually very high melting solids, often having melting points above 1000 °C
H + H H-Hcovalent bond
H + Cl H-ClPolar covalent bond
2) Covalent Bonds Results from sharing of electrons by two atoms such as H-H, Cl-Cl, H-Cl and so on.
Polar covalent bond ( between two atoms different in electronegativity)
Polar Covalent Bonds: Unevenly matched, but willing to share.
Chemical reactions
Chemical reaction
Reaction without electron transfer Reaction with electron transfer
2H2 + O2 2H2O Sn 2 Sn 4+ 2e
1-Combination 1-Oxidation (loss of electrons)
Cl + CH3Br CH3Cl + Br Fe3
+ e Fe2
2-Substitution 2-Reduction (gain of electrons)
BF3 + NH3 BF3 NH3 MnO4 + 5 e + 8H Mn + 4H2O2
3-Addition 3-Redox reaction(oxidation-reduction)
4-Combustion
CH4 + 2O2 CO2 + H2O
A solution is a homogenous mixture of 2 or more substances
The solute is)are) the substance)s) present in the smaller amount)s)
The solvent is the substance present in the larger amount
Solution Solvent Solute
Soft drink )l) H2O Sugar
An electrolyte is a substance that, when dissolved in water, results in a solution that can conduct electricity.A nonelectrolyte is a substance that, when dissolved, results in a solution that does not conduct electricity.
nonelectrolyte weak electrolyte strong electrolyte
Acid–base reactions
Acids : Is the substance that produces H+ ions when it dissolved in Waterstrong acid; it is a strong electrolyte.weak acid:it is a weak electrolyte.
Acids can be divided into two classes
Strong Acids : Completely dissociate into its ions eg: HCl, HBr, HNO3 and H2SO4
HCl (aq) → H+ (qa) + Cl- (aq) 100% dissociation
Weak acids : is the one dissociate incompletely into its ions eg: CH3COOH.
CH3COOH ↔ H + (aq) + CH3COO- (aq) 1% dissociation
Base : Is the substance that produces OH- ions when it dissolved in water
strong base; it is a strong electrolyte.weak base:it is a weak electrolyte.
Bases: can be divided into two classes Strong Bases : Completely dissociate into its ions eg: NaOH and KOHNaOH (aq) → Na+ (qa) +OH- (aq)
100% dissociation Weak Base : is the one dissociate incompletely into its ions eg: ammonia.
NH3(aq) + H2O(l) ↔ NH4 + (aq) + OH- (aq)
1% dissociation
Examples of the acid-base reactions: Reaction of Sodium hydroxide and Nitric acid & reaction of Potassium hydroxide and Sulfuric acid.
The Brønsted - Lowry theory of acids and bases.A Brønsted – Lowry acid: is a species which donates a proton (H+ ion) to another species.A Brønsted – Lowry base: is a species which accepts a proton from another species. You must have a reaction in order to name a species as a Brønsted - Lowry acid (B-L acid) or base.
Example HCl(aq) + H2O (l) H3O+
(aq) + Cl-(aq)
HCl is the B-L acid, it donates the proton to the H2O which is the B-L base since it accepts the proton (H+ion)
Example NH3(g) + H2O(l) NH4
+(aq) + OH-
(aq)H2O is the B-L acid, it donates the proton to the NH3 which is the B-L base since it accepts the proton (H+ion).
Quiz time
Mention Brønsted - Lowry theory of acids and bases for the fowlloing reaction
NH3(g) + H2O (l) NH4+
(aq) + OH-(aq)
HCl(aq) + H2O (l) H3O+(aq) + Cl-
(aq)
NH3(aq) + H2O(l) ↔ NH4 + (aq) + OH- (aq)
What is type of base for NH3 ?
HCl (aq) → H+ (qa) + Cl- (aq)
What is type of acid for HCl ?
N,C, F,O ,
Order according for electronegativity ?
Fe3
+ e Fe2
Cl + CH3Br CH3Cl + Br
BF3 + NH3 BF3 NH3
CH4 + 2O2 CO2 + H2O
Mention types of reaction ?
Student Question
Fe3
+ e Fe2
Cl + CH3Br CH3Cl + Br
BF3 + NH3 BF3 NH3
CH4 + 2O2 CO2 + H2O
Mention types of reaction ?BaseAcidssoluteelectrolyte
Define and give example
Mention Brønsted - Lowry theory of acids and bases for the fowlloing reaction
NH3(g) + H2O(l) NH4+
(aq) + OH-(aq)
HCl(aq) + H2O (l) H3O+(aq) + Cl-
(aq)
NH3(aq) + H2O(l) ↔ NH4 + (aq) + OH- (aq)
What is type of base for NH3 ?
HCl (aq) → H+ (qa) + Cl- (aq)
What is type of acid for HCl ?
N,C, F,O ,
Order according for electronegativity ?
AssignmentsGroup A and Group B
Noor El-Din AdelMohamad Abd El FatahAli Mahmoud Ahmad
Combustion reaction
Naamat Hafez Mana Allah MostafaPassant Ahmad Hamza
Substitution reaction in industry
Ashraf MoahamadEl Amir Said TawfikIbrahim ShahaatAhmad Mahmoud Raafat AbdAllah
Application of redox reaction
Abeer El Said -Haidy Adel- Ali HassanHossam Hassan- Yehia HamdyYoussef Ali
Physical properties of matter
RECOMMENDED TEXTBOOKS:
1-Raymond Chang. Chemistry. 10th ed. 20092-Zumdehl. International edition. 2009