bonding part one

Question 1

Tetrahedral

Answer 1

• central atom is surrounded by 4 bonding pairs and 0 lone pairs
• if angles were measured they would be found to be 109.5 degrees

Question 2

Pyramidal

Answer 2

-central atom is surrounded by 3 bonding pairs and one lone pair

Question 3

V shaped or bent

Answer 3

central atom is surrounded by 2 bonding pairs and 2 lone pairs

Question 4

Trigonal Planar

Answer 4

central atom is surrounded by 3 bonding pairs and 0 lone pairs

Question 5

Linear

Answer 5

only two atoms bonded to each other

central atom is surround by 2 bonding pairs and 0 lone pairs

Question 6

Polar

Answer 6

the bond dipoles do not cancel

Question 7

non-polar

Answer 7

the bond dipoles do cancel

Question 8

what are some general rules for polarity

Answer 8

• all molecules will be nonpolar if all the atoms including the central atom have the same electronegativity
• tetrahedral,Trigonal Planar & linear molecules will be polar if one or more atom(s) surrounding the central atom are different
• pyramidal & bent shaped molecules will be polar
• Hydrocarbons are nonpolar,but they become polar if one or more atom(s) is/are different

Question 9

Covalent bond

Answer 9

the force of attraction that exists between two nonmetallic atoms whose nuclei share an attraction for the same paris of electrons

Question 10

Electronegativity

Answer 10

is the tendency of an atom to attract electrons to itself when it is chemically combined with another atom.

Question 11

what are some trends in electronegativity

Answer 11

• increase in electronegativity from left to right within a period
• decrease in the element electronegativity from top to bottom within a group

Question 12

Solubility

Answer 12

Refers to the ability of a substance to dissolve in a given solvent
General rule is “like dissolves like”
Polar will dissolve polar,nonpolar will dissolve nonpolar

Question 13

Intramolecular forces

Answer 13

are the forces within a molecule. They are the forces that keep the atoms in a compound stuck to each other. In other words,thy are just chemical bonds 
-covalent bonding
Ionic bonding 
Metallic bonding
Network covalent bonding

Question 14

Intermolecular forces

Answer 14

Are the forces between molecules. They are the forces that attract two covalent molecules to one another. They are the simultaneous attractions between neighbouring molecules
Intermolecular forces
LDF, D-D forces( van de waals forces)
Hydrogen Bonding
Intermolecular forces- attractions between molecules. They are responsible for the state at room temp,hardness,melting and boiling point.

Question 15

Intermolecular attractions

Answer 15

Intermolecular forces- attractions between molecules. They are responsible for the state at room temp,hardness,melting and boiling point.

Question 16

LDF

Answer 16

Attractions by protons in the nuclei of one molecule for electrons in a nearby molecule
-occurs in all molecules
(And only molecular compounds)
-factors affecting the strength of LDF are the number of electrons per molecule and the molecular shape.
As number of e per molecule increases so does the strength of LDF. The closer molecules get together=higher LDF, the simpler the shape=Higher LDF

Question 17

Dipole dipole forces

Answer 17

The force of attraction between the oppositely charged ends of dipoles in adjacent molecules
-polar molecules have molecular dipoles where one region in the molecule has a partial negative charge and another region has a partial positive charge
Occurs between polar molecules in molecular compounds

Question 18

Hydrogen bonding

Answer 18

The simultaneous attraction whereby the nucleus of a H atom is attracted to lone pairs of e on atoms of F,N or O in neighbouring molecules
Conditions for h bonding:
Molecule must contain a highly electronegative element(F O or N) hydrogen must be bonded to the highly electronegative element

Question 19

Explain in condensation in terms of LDF

Answer 19

Condensation is the change from a gas to a liquid. As gas molecules slow down, these LDF will be able to pull the molecules together-condensation (molecules are closer together in the liquid state than the gas

Question 20

Ionic bonds

Answer 20

The simultaneous attraction of an ion by its surrounding ions of opposite charge within an ionic crystal) a 3D, continuous, repeating pattern of a pos and neg ions in an ionic solid

Question 21

What are the properties of ionic compounds

Answer 21

State- solids at room temp
Hardness -hard and brittle
Melting point-high melting and boiling point
Solubility in water-usually high(some exceptions)
Conductivity-poor conductors in solid state

Question 22

Explain the properties of ionic compounds

Answer 22

Add or refer to exercise

Question 23

Describe the three types of compounds and their type of bond

Answer 23

Ionic compound- is held by bonds between cations and anions. Metals(low electronegativity) TRANSFER or lose their valence electrons to nonmetals(high electroneg)
Molecular compound- is held together by covalent bonds. The nonmetallic elements SHARE their valence electrons
Metals. Are held together by metallic bonding. Metallic bonds form between atoms that have low electronegativity was. The metals do not hold on their valence e strongly. They have empty valence orbitals. The loosely held valence electrons are free to move from one valence orbital to the next
Can be thought as a group of cations in a “sea” of electrons

Question 24

Why are metals Malleable & ductile ?

Answer 24

Metals are very malleable and du tile bc the shifting of the positive ions do not result in repulsion, the metallic bond Is not fixed. As the metal ions move,the free moving valence electrons more too. The cations slide pass each other with the sea of electrons acting as a lubricant

Question 25

Why are metals good conductor

Answer 25

Electricity= the flow of e The free election character of metals explains why they are excellent conductors of electricity (think of loosely held, able to flow electrons/sea of e)

Question 26

Why do metals have a range of melting ?

Answer 26

This because the larger the number of electrostatic attractions between the stationary positive ions and the valence electrons the higher the melting point

Question 27

Network covalent bonding

Answer 27

Is the simultaneous attraction of every atom to adjacent atoms by covalent bonds ,within a 3D lattice atoms A network solid is a giant rigid structure in which atoms are covalent bonded together in a continuous 3D array. The bonds are very strong and very directional in a 3D network

Question 28

What are the three network covalent solids

Answer 28

Cn SiC SiO2

Question 29

What are properties of network solids

Answer 29

Strong and hard High melting point Not soluble in water Do not conduct

Question 30

Explain in terms of bonding present why network covalent solids are so hard and have very high boiling points

Answer 30

Network covalent solids are hard and have high melting points due to each atom within the network solid being bound in 3D to four other atoms and s on. This gives a tight 3D network where each atom as so tetrahedral arrangement about it. All atoms are held in rigid positions, thus making it very difficult to break open.

Question 31

Explain in terms of bonding present, why network covalent solids do not conduct electricity

Answer 31

Network covalent solids do not conduct electricity due to the fact that electrons are not free to move. All valence e within the network solid are involved in covalent bonds therefor can both move about

Question 32

Explain in terms of bonding present why molecular compounds are soft and have low melting points

Answer 32

The individual molecules of a molecular compound are held together by weak intermolecular forces. Large amounts of energy are not needed to break these forces making them soft and causing them and causing them to have low melting points

Question 33

Explain in terms of bonding present why some molecular compounds are soluble in water and others are not

Answer 33

Solubility in water(polar) will depend on the polarity of the molecular compound. If the intermolecular force , dipole dipole is present(molecule is polar), then the molecular compound will be soluble in water. It the molecular compound is nonpolar, then it will not be soluble in water. This is because like dissolve like

Question 34

Explain in terms of of bonding present why molecular compounds do not conduct electricity in either state

Answer 34

Molecular compounds do not conduct electricity in either state be there are no charged particles available to move about. There are no ions present and all electrons are held tightly. Very electronegative nonmetallic atoms are involved in sharing for stability of the atoms

Question 35

Explain why ionic compounds are hard and have high melting points

Answer 35

Physical energy is not enough to break the bonds(to break an ionic bond you have to separate the individual +&- ions. Each ion has several ionic bonds to its neighbour. Therefore it will Require a large amount of energy to break all these bonds.), which accounts for its hardness. -large amounts of heat energy is required to get the ions moving fast enough to break the ionic bonds, which accounts for the high melting point

Question 36

Why do ionic compounds have high solubility in water ?

Answer 36

Water is polar. Partially positive ends will attract the - ions in the ionic crystal, the partially negative end will attract the positive ions in the ionic crystal. The ionic crystal separated into ions in solution.

Question 37

Why is there reclusion in ionic compounds?

Answer 37

If the crystal is bent or hit,the positive and negative ions may be forced away from ions of opposite charge and closer to ions with the same charge. This results in repulsion and the crystal shatters

Question 38

Explain the difference of how ionic compounds conduct in each state

Answer 38

(Note in order for substances to conduct, there must be movement of charged particles) in solid state, ions are not free to move because they are fixed in a position by ionic bonds. In the liquid state and aq state, the ionic bonds have been broken and ions are free to move towards an electrode of opposite charge