CHEMICAL BONDING DEFINITION OF A CHEMICAL BOND A
CHEMICAL BONDING
DEFINITION OF A CHEMICAL BOND • A CHEMICAL BOND IS A MUTUAL ATTRACTION BETWEEN THE NUCLEI AND VALENCE ELECTRONS OF DIFFERENT ATOMS- THAT BINDS THE ATOMS TOGETHER
TYPES OF CHEMICAL BONDING • WHEN A BOND FORMS, THE VALENCE ELECTRONS OF EACH ATOM, MOVES INTO DIFFERENT POSITIONS- • THE FORMATION OF A BOND MAKES THE ATOMS MORE STABLE.
• SINCE WE KNOW THAT METALS LOSE ELECTRONS AND FORM POSITIVE IONS AND • NONMENTALS GAIN ELECTRONS AND FORM NEGATIVE IONS • THE ATTRACTION BETWEEN THE POSITIVE AND NEGATIVE IONS FORMS AN ELECTRICAL ATTRACTION- CALLED AN IONIC BOND.
• ATOMS THAT DO NOT COMPLETELY GAIN OR LOSE THEIR VALENCE ELECTRONS WILL SHARE THEIR VALENCE ELECTRONS. • THE SHARING OF A PAIR OF ELECTRONS BY TWO ATOMS IS CALLED A COVALENT BOND.
COVALENT BOND • IF THE PAIR OF ELECTRONS ARE SHARED EQUALLY BETWEEN THE TWO ATOMS, THE BOND IS CONSIDERED TO BE NON-POLAR • NON-POLAR BONDS MEANS THAT THERE IS NO POSITIVE OR NEGATIVE SIDE OF THE BOND.
IONIC BOND OR COVALENT BOND • REMEMBER: ELECTRONEGATIVITY IS THE MEASURE OF AN ATOMS ABILITY TO ATTRACT ELECTRONS. • WE CAN DETERMINE THE TYPE OF BOND FORMED BETWEEN TWO ATOMS, BY MEASURING THE DIFFERENCE BETWEEN THE TWO ATOM'S ELECTRONEGATIVITIES.
BOND TYPE DETERMINED BY ELECTRONEGATIVITY DIFFERENCE • COMPARE THE ELECTRONEGATIVITY OF CESIUM AND CHLORINE. • ELECTRONEGATIVITY OF CESIUM= 0. 7 • ELECTRONEGATIVITY OF CHLORINE= 3. 0 • DIFFERENCE BETWEEN HE TWO ATOMS= 2. 3 •
DIFFERENCE IN ELECTRONEGATIVITY • WHEN THE DIFFERENCE OF ELECTRONEGATIVITY IS GREATER THAN 1. 7 THE BOND IS CONSIDERED TO BE IONIC
TYPES OF BONDS: • COMPARE THE ELECTRONEGATIVITY DIFFERENCE BETWEEN SULFUR (ELECTRONEGATIVITY= 2. 5) • AND HYDROGEN (2. 1) • AND CESIUM (0. 7) • AND CHLORINE (3. 0) • 2. 5 -2. 1= 0. 4 BOND TYPE= POLAR COVALENT • 2. 5 -0. 7= 1. 8 BOND TYPE IS IONIC • 3. 0 -2. 5= 0. 5 BOND TYPE IS POLAR COVALENT
POLARITY • DEFINITION OF POLARITY A PLANE OR LINE WITH A POSITIVE AND NEGATIVE END (OR POLE) • I. E. - A MAGNET
A POLAR COVALENT BOND • A COVALENT BOND- SHARED ELECTRONS BETWEEN TWO ATOMS, WHERE ONE END OF THE BOND IS (+) AND ONE END IS (-) • CONSIDER THE BOND BETWEEN SULFUR AND HYDROGEN • (SULFUR)------(HYDROGEN) • WHICH END OF THE BOND IS (+) AND WHICH END IS (-)
POLAR COVALENT BOND • SINCE SULFUR HAS AN ELECTRONEGATIVITY VALUE OF 2. 5 AND HYDROGEN HAS A VALUE OF 2. 1 • SULFUR IS THE NEGATIVE END OF THE BOND AND HYDROGEN IS THE POSITIVE END OF THE BOND • CONSIDER THE BOND BETWEEN SULFUR AND CHLORINE • WHICH END IS POSITIVE AND WHICH IS NEGATIVE
SECTION REVIEW • PAGE 177 QUESTIONS 1 -6 • Expect quiz on these questions.
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