Bonding 2017-18.ppt

Chemical

Bonding

A bond is when 2 or

more atoms combine

to:

1.

Lower their energy

Covalent Bonds

• _{A covalent bond is a bond in which}

the atoms share electrons in an overlapping manner.

• They are formed between two non-metals.

• _{There are two types of covalent}

Non-polar

Covalent Bonds

• A non-polar covalent bond is a covalent bond in which the bonding electrons are shared equally by the bonded atoms, resulting in a balanced

Non-polar

Covalent Bonds

• _{Examples of non-polar covalent}

bonds are the diatomic elements.

Polar Covalent

Bonds

• _{A polar covalent bond is a}

covalent bond in which the

bonded atoms have an unequal attraction for the shared

• One way to tell the difference between a polar and non-polar covalent bond is by the

electronegativities. If the

electronegativities are equal the compound is non-polar. If the electronegativities are not equal the compound is polar.

• _{Another way to tell a difference}

between a polar and non-polar molecule is if a molecule is

symmetrical, its non-polar and if it isn’t, it is polar.

• _{Water is a polar molecule.}

• Molecules can be held together by single, double, or even triple covalent bonds.

• In a single bond the atoms share 2 electrons.

• In a double bond the atoms share 4 electrons.

• In a triple bond the atoms share 6 electrons.

Covalent

Ionic Bonding

• An ionic compound is composed of a positive and a negative ions that are combined so that the number of positive and negative charges are equal.

•

_{Example: NaCl}

Bonding

• One way to tell if a compound is covalent or ionic is by the

electronegativities of the atoms. If you subtract the electronegativities of both atoms and you come out

• _Example:

HCl:

H has a electronegativity of 2.5 Cl has a electronegativity of 3.2 Therefore it is a polar covalent

molecule.

Polyatomic Ions

• A polyatomic ion is a compound of two or more covalently bonded

atoms with a charge.

• These ions are found on reference table E.

• Examples: OH-, NH

VSEPR Theory

• _{Valence Shell Electron Pair Repulsion}

Molecule Type Example Shape

AB₂ BeF₂ Linear

AB₃ BF₃ Trigonal planar AB₄ CH₄ Tetrahedral

AB₃E NH₃ Trigonal pyramid AB₂E SnCl₂ Bent

• _{Metallic bonding is the chemical}

bonding that results from the

attraction between metal atoms and the surrounding sea of

electrons.

Intermolecular

Forces of

Attraction

Intermolecular forces are the forces of attraction between

Dipole-Dipole

Forces

• _{The forces of attraction}

Hydrogen Bonding

• Hydrogen bonding is a very

strong dipole-dipole attraction that only occurs between

hydrogens and small

electronegative atoms such as nitrogen, oxygen, and fluorine.

Van der Waal

Forces

• _{Van der Waal forces are forces that} hold non-polar molecules together. • _{Some examples are the diatomic}

Network Solids

• A network solid is an strong on going link of non-polar covalent bonds.

• Examples:

–Diamonds

–Silicon

–_{Sand (SiO2)}

Bonds

Bonds Forces of Forces of Attraction

Attraction

Non-polar Van der Waals Polar Dipole-Dipole

Ionic Hydrogen

Bonding Metallic Ionic Solids

Network Solids

Chemical

Bonding

1) Which bond has the greatest degree of ionic character?

a) I-Cl b) Cl-Cl c) H-Cl d) K-Cl

2) Which compound contains ionic bonds?

a) HBr b) NaBr

c) C₆H₁₂O₆ d) CO₂

3) A characteristic of ionic solids is that they:

a) Have low boiling points b) Are noncrystalline

c) Conduct electricity

d) Have high melting points

4) Which substance will conduct electricity in both the solid

phase and the liquid phase?

a) H₂ b) Ag c) HCl d) AgCl

5) A substance that has a melting point of 1074 K conducts electricity when dissolved in water, but does not

conduct electricity in a solid phase. The substance is most likely:

a) A molecular solid b) An ionic solid

c) A network solid d) A metallic solid

6) A molecule of ammonia (NH₃) contains:

a) Covalent bonds, only

b) Both covalent and ionic bonds

c) Neither covalent and ionic bonds d) Ionic bonds, only

7) The correct electron dot

formula for hydrogen chloride is:

a) H Cl b) H Cl c) H Cl d) H Cl

8) Which formula represents a tetrahedral molecule?

a) CaCl₂ b) Br₂

c) CH₄ d) HBr

9) Two atoms of element A unite to form a molecule with the

formula A₂. The bond between the atoms in the molecule is:

a) Polar covalent

b) Non-polar covalent c) Electrovalent

d) Ionic

10) What type of bonding is found in the molecule HBr?

a) Non-polar covalent b) Polar covalent

c) Ionic

d) Metallic

11) Which type of bond is contained in a water

molecule?

a) Polar covalent b) Electrovalent c) Ionic

d) Non-polar covalent

12) Which molecule is a dipole?

a) HCl b) CH₄ c) H₂ d) N₂

13) Which structural formula represents a non-polar

symmetrical molecule?

a)

b)

c)

d)

14) The strongest hydrogen bonds are formed between molecules of:

a) H₂Te b) H₂S c) H₂O d) H₂Se

15) Which kind of bonds are found in a sample of H₂O?

a) Both covalent and hydrogen bonds b) Both ionic and hydrogen bonds

c) Hydrogen bonds, only d) Covalent bonds, only

16) Which of the following noble gases has the lowest normal boiling point?

a) Kr b) Ne c) Xe d) Ar

17) Which type of bonding accounts for the unusually high boiling point of water?

a) Network bonding b) Covalent bonding

c) Van der Waals forces d) Hydrogen bonding

18) The attraction which exists between carbon dioxide

molecules in solid carbon dioxide is due to

a) Ionic bonds

b) Hydrogen bonds

c) Van der Waals forces d) Molecule-ion forces

19) Helium may be liquefied at low temperature and high

pressure primarily because of

a) Van der Waals forces b) Hydrogen bonding

c) Covalent bonds d) Ionic attraction

20) Van der Waals forces of attraction between molecules decrease with

a) Decreasing # of electrons and increasing distance between the molecules

b) Increasing # of electrons and decreasing distance between the molecules

c) Decreasing # of electrons and decreasing distance between the molecules

d) Increasing # of electrons and increasing distance between the molecules

21) Molecule-ion attractions are found in:

a) KBr _(s) b) CO _(g)

c) NaCl _(aq) d) Cu _(s)

22) Which formula represents a molecular solid?

a) NaCl b) Cu

c) C₆H₁₂O₆ d) KF

23) Which compound is a poor conductor of heat and

electricity and has a high melting point?

a) H₂O b) CO₂ c) SiO₂ d) N₂O

24) What type of bonds are present in a strip of

magnesium ribbon?

a) Van der Waals b) Metallic

c) Ionic

d) Covalent

25) Which substance contains positive ions immersed in a

sea of mobile electrons?

a) CuO b) SiO₂ c) Cu d) O₂