Unit 4

Question 1

How to determine valence electrons?

Answer 1

Group (column) #

Question 2

Chemical bonds (forces)

Answer 2

Forces that hold atoms together by transfer or sharing electrons

Question 3

Covalent bond

Answer 3

Electrons are shared resulting in molecule. Polar and non polar

Question 4

Ionic bond

Answer 4

Formed from ions + or - in which electrons are transferred. + ions are cations, - ions are anions.

Question 5

Exothermic energy

Answer 5

Energy released from system to surroundings when a bond is formed or broken.

Question 6

Electronegativity

Answer 6

Ability of the nucleus of one element to attract electrons of another element to obtain an octet.

Question 7

Electronegativity generally ______ from left to right within a period.

Answer 7

Increases. As size of atom decreases, there is more attraction to nucleus.

Question 8

Electronegativity generally ______ from top to bottom within a group.

Answer 8

Decreases. The size of the atom increases as more energy levels are added.Bottom left to top right increases.
             Higher
              /
             /      Increases
Lower. /

Question 9

Metals want to lose electrons so they have ____

Answer 9

Low electronegativity. Small attraction for valence electrons.

Question 10

Nonmetals want to gain electrons so they have _____

Answer 10

High electronegativity. High attraction for valence electrons

Question 11

The larger the difference between electronegativities of two nonmetals, the more ___ the bond will be

Answer 11

Polar

Question 12

Ionic bonds en>1.8 in groups ___

Answer 12

1,2,6,7

Question 13

Polar bonds between 1.8>en>.4

Answer 13

Everything else

Question 14

Nonpolar covalent bonds if en<.4

Answer 14

C-H only compounds, diatomic elements

Question 15

Endothermic energy

Answer 15

Absorbed from surroundings to system when a bond is formed or broken.

Question 16

The reason elements form bonds

Answer 16

Usually to go to lowest energy state

Question 17

Molecule

Answer 17

Smallest unit of covalently bonded elements

Question 18

Formula unit

Answer 18

Smallest unit of an ionic bond

Question 19

Subscripts in a formula give the number of ____ of that element in a molecule.

Answer 19

Atoms

Question 20

Coefficients

Answer 20

Number in front of a compound giving the total number of molecules of that compound

Question 21

Ionic bonds

Answer 21

• Electrons are transferred from one atom to another
• ions are formed when electrons are gained or lost
• difference in electronegativity values is great

Question 22

Cation

Answer 22

Electrons lost-metals

+ion

Question 23

Anion

Answer 23

Electrons gained-nonmetals

-ion

Question 24

Formation of ionic bonds is _______

Answer 24

Exothermic

Question 25

Polyatomic atoms

Answer 25

Charged group of covalently bonded atoms. E entire group will bond to another ion according to its charge, + or -

Question 26

Nonpolar covalent bonds

Answer 26

Electrons between elements as shared equally. Equal attraction for shared electrons. Balanced distribution of charge. No dipoles

Question 27

7 diatomics

Answer 27

HOFBrINCl

Question 28

Noble gases have _____ electronegativity

Answer 28

Zero

Question 29

Polar covalent bonds

Answer 29

Shared unequally creating dipoles

Question 30

Polar bond

Answer 30

A covalent bond in which there is an unequal attraction for the shared electrons and the resulting unbalanced distribution of charge

Question 31

The larger the difference between the electronegativities of two nonmetals the more _____the bond will be

Answer 31

Polar

Question 32

Oxidation numbers

Answer 32

The real or apparent charge an Atom or ion has when all bonds are assumed to be ionic. (How many electrons would an Atom want to lose or gain to have eight electrons?)

Question 33

Charged atom

Answer 33

Indicates whether the atom gained electrons (-) or lost electrons (+). Write number followed by + or -. Value indicates how many electrons were gained or lost.

Question 34

Oxidation number rules

Answer 34

- any atom in free state is 0 - any simple ion is the charge on that ion - O usually -2, exception peroxides O is -1 - H usually +1, F always -1

Question 35

A polyatomic ion is equal to

Answer 35

The sum of the individual oxidation numbers

Question 36

For a neutral molecule, the sum of all charges is equal to

Answer 36

Zero. True of all compounds

Question 37

Oxidation numbers per group

Answer 37

Group 1=+1 Group 2=+2 Group 3=+3 Hydrides=-1 Group 7=-1 only if bonded with metal. Can have multiple with nonmetals. Group 6=-2 only with metal. Can have multiple with nonmetals. Group 5=-3 only with metal. Can have multiple with nonmetals.

Question 38

Elements with 2 oxidation numbers

Answer 38

- Iron Fe +2 iron ii Fe +3 iron iii - copper Cu +1 Cu +2 - tin Sn +2 Sn +4 - mercury Hg2 2+ Hg +2

Question 39

For binary compounds (2 elements) composed of metal (cation) and nonmetal (anion) rules for writing formula (ionic compounds)

Answer 39

-name metal first using full name -figure charge and put in ( ) if > 1 -name nonmetal 2nd, drop ending and add ide -no prefixes Ex:NaCl sodium chloride Ex: PbCl4 Lead (iv) chloride

Question 40

Prefixes for number of atoms

Answer 40

``` 1 mono 2 di 3 tri 4 tetra 5 penta 6 hexa 7 hepta 8 octa ```

Question 41

Binary compound of two nonmetals (no ions) chemical formula rules

Answer 41

-least electronegative written first using full name, no prefixes unless more than one atom -most electronegative is second and always has prefix -drop ending add ide -drop final o or a of premix if element starts with vowel Ex: As2O5 diarsenic pentoxide

Question 42

Compounds containing polyatomic ions (more than 2 elements) formula rules

Answer 42

-Metals are named first using the full element name -polyatomic ions retain its name whether its positive or negative Ex: NH4Cl ammonium chloride

Question 43

Exceptions to oxidation numbers rules

Answer 43

-peroxides- oxygen with a -1 charge. Nonmetals with O2 is not a peroxide. Ex: Li2O2 lithium peroxide CaO2 calcium peroxide