1.1 Structure Of Water And Hydrogen Bonding

Question 1

What is matter?

Answer 1

• anything that takes up space and has mass

Ex. Rocks, metals, oils, gases, organisms, etc.

Question 2

What is an element? How many occur in nature? (2)

Answer 2

• A substance that cannot be broken down into another substance by chemical reactions
• 92 elements occur in nature
  (Periodic table)

Question 3

What is a compound?

Answer 3

• A substance consisting of two or more different elements combined in a fixed ratio
  Ex. H20, NaCl

Question 4

What percentage of the 92 Naturally occurring elements are essential?

Answer 4

20-25% are essential to survive and reproduce

Question 5

What essential elements make up a large amount of living matter, and what percent do they make up? (3)

Answer 5

• CHNOPS
• 96% living matter
• Sulfur is in protein R groups

Question 6

What are trace elements?

Answer 6

• Of the 92 naturally occurring elements, these are required by an organism in very small quantities
  Ex. Fe, Mg, Ca, etc.

Question 7

Why are essential elements essential? In other ways, what roles do they play in the human body?

Answer 7

CHNOP(S) please a vital role in the formation of cells and cellular components
Ex. Proteins, nucleic acids, etc.

Question 8

What are a few examples of trace elements in their purpose in the human body? Use iron, zinc and copper as an example. (3)

Answer 8

Iron- necessary for blood production
Copper - works with iron to produce blood cells
Zinc - helps the body’s immune system

Question 9

Which way do groups and periods go on the periodic table?

Answer 9

• Groups are vertical

- periods are horizontal

Question 10

What does the Bohr model show? (3)

Answer 10

• shows electrons orbiting the nucleus of an atom
• electrons are placed on shells around the nucleus
• each shell is a different energy level and can hold up to a certain number of electrons

Question 11

What is the Lewis dot model? (4)

Answer 11

• simplified Bohr diagrams
• does not show energy levels
• only shows electrons in the valence shell
• Electrons are placed around the element symbol

Question 12

Why do elements form chemical bonds with other elements?

Answer 12

• They want to be stable

Question 13

What is the octet rule?

Answer 13

• elements will gain, lose, or share electrons to complete their valence shell and become stable (like noble gases)

Question 14

What is a chemical bond?

Answer 14

• Attraction between two Atoms, resulting from the sharing or transferring of valence electrons

Question 15

What is electronegativity?

Answer 15

• The measure of an atoms ability to attract electrons to itself

Question 16

What is a covalent bond? (3)

Answer 16

• when two or more atoms share electrons
• usually between two nonmetals
• forms molecules and compounds

Question 17

What are the two types of covalent bonds?

Answer 17

-polar and non polar

Question 18

What is a non-polar covalent bond?

Answer 18

• Electrons are shared equally between two atoms

Ex. O2, HOFBrINCl

Question 19

What is a polar covalent bond? (2)

Answer 19

• electrons are not shared equally between two atoms
  Ex. H2O
• unequal sharing of Electrons results in partial charges on oxygen and hydrogen

Question 20

What is an ionic bond?

Answer 20

• The attraction between oppositely charged atoms (ions)

- usually between a metal and nonmetal, where metals transfer electrons to nonmetals

Question 21

What do Ionic bonds form?

Answer 21

• Ionic compounds and salts

Ex. NaCl, LiF

Question 22

What are cations and anions?

Answer 22

• positively charged ions and cations

- negatively charged ions are anions

Question 23

How do hydrogen bonds form? (2)

Answer 23

• The partially positive hydrogen atom in one polar covalent molecule will be attracted to one electronegative atom in another polar covalent molecule
• H bonds are known to be weak
• INTERMOLECULAR

Question 24

What is the difference between inter-and intramolecular bonds?

Answer 24

• Bonds that form between molecules are INTER

- Intra means inside

Question 25

Why do hydrogen bonds occur?

Answer 25

• when a hydrogen atom is bonded to an electronegative atom (usually O, N, or F) the electrons are not being shared equally between atoms (remember it’s a covalent bond)
• This causes oxygen to have a partial positive charge on the electronegative atom to have a partial negative charge

Question 26

How do the hydrogen bonds change the structure of water?

Answer 26

• hydrogen bonds between water make it more structured than most liquids
• water molecules move a lot because hydrogen bonds form, break, and reform with great frequency