Ch. 2.1 - Chemical Bonding

Question 1

types of chemical bonds (3)

Answer 1

• covalent bonds: non polar = equal sharing, and polar = unequal sharing
• ionic bonds: one donates and one receives
• hydrogen bonds: between different molecules

Question 2

principles of chemical bonding (2)

Answer 2

• based on the sharing/donating/receiving of electrons so both end up with completed outer shells
• sometimes electrons are shared equally (covalent) or unequally because one element attracts electrons more strongly (polar covalent)

Question 3

electronegativity

Answer 3

• atoms attraction for shared electrons
• if one atom in a bond is more electronegative then the other bond is polar -> one area will have a slight +. charge and the other is a slight -

Question 4

electrons in a covalent bond

Answer 4

in a constant tug of war

Question 5

ionic bonds

Answer 5

• electron stealing or donating
• gives up electron -> positive ion
• takes electron -> negative ion

Question 6

hydrogen bonds

Answer 6

form between slightly positive hydrogen of one molecule and slightly negative oxygen or nitrogen etc of another molecule

Question 7

water (3)

Answer 7

• universal solvent - dissolves more substances than any other chemical, especially gases and ions
• no other natural substances that occur in quantity as liquids at the earth’s surface
• can dissolve many other molecules, especially those held together by ionic or polar covalent bonds

Question 8

hydrogen bonding of water

Answer 8

attraction between hydrogen and oxygen of different water molecules

Question 9

solution

Answer 9

a liquid that is a mixture of two or more substances

Question 10

solvent

Answer 10

dissolving agent - usually liquid (water=most versatile)

Question 11

solute

Answer 11

substance thats dissolved in a solution (often solid)

Question 12

hydrophilic and hydrophobic

Answer 12

• philic=water loving

- phobic=water fearing

Question 13

unpredictable properties of water (5)

Answer 13

• should only exist as a gas at earths temp
• high heat capacity - takes a lot of heat to change the temp (need to break hydrogen bonds)
• high viscosity and cohesion and adhesion - meniscus water strider
• ice forms tetrahedral structure which holds water molecules far apart so ice is less dense
• evaporates and freezes at much higher temps

Question 14

specific heat

Answer 14

temp/energy needed to raise 1g of water to 1 degree

Question 15

cohesion

Answer 15

• tendency of molecules of the same kind to stick together
• much stronger for water than other liquids
• water strider has evolved to take advantage of cohesion

Question 16

heat

Answer 16

total amount of energy associated with molecular movements

Question 17

temperature

Answer 17

the intensity of heat

Question 18

water warms slowly but contains a lot of heat (2)

Answer 18

• oceans are relatively cold, but they contain 1000x more heat than the atmosphere
• water moderates the temp of the earth

Question 19

unexpected properties of water pt 2 (3)

Answer 19

• heat is absorbed to break h-bonds and is released when they form requires much more heat than if there were no h-bonds
• when h-bonds form (as when ice forms a lattice structure) heat is released
• when sweat evaporates water is going from a liquid to a gas, this breaks the h-bonds holding it as a liquid. as h-bonds break they absorb heat, thus cooling your skin