Chapter 2: Chemical Principles

Question 1

What is the smallest chemical unit of matter?

Answer 1

an atom

Question 2

What is an element?

Answer 2

matter that is composed of one type of atom (eg. carbon, nitrogen, oxygen)

Question 3

What is a molecule?

Answer 3

• two or more atoms combined
• it can be the same type of atom (eg. N2)
• it can be different atoms (eg. CO2) to form a compound

Question 4

Order the following bonds from strongest to weakest: Ionic, hydrogen, covalent

Answer 4

1. Covalent
2. Ionic
3. hydrogen

Question 5

Every atom has a centrally located nucleus. What parts make up a nucleus chemically? (2)

Answer 5

• protons that are positively charged
• neutrons that are neutrally charged

Question 6

Does the nucleus have a positive, negative, or neutral charge?

Answer 6

positive

Question 7

Is the nucleus stable? (2)

Answer 7

• no, hence it does not participate in chemical reactions
• electrons participate

Question 8

What is the charge and location of electrons?

Answer 8

• negatively charged
• circle the nucleus

Question 9

How do we get a neutral charge on an atom?

Answer 9

• an equal number of electrons and protons

Question 10

How are electrons surrounding the nucleus?

Answer 10

• unlike protons and neutrons that are densely packed in the nucleus, the lighter electrons orbit the nucleus in “shells”
• electron shells correspond to different energy levels

Question 11

How do chemical bonds form between atoms?

Answer 11

Through interactions of electrons in their outer shells

Question 12

What is the goal of every atom, and how is it achieved?

Answer 12

• the goal is to become chemically stable
• achieved by filling the outermost shell with electrons by combining together to form molecules

Question 13

What is a cation?

Answer 13

An atom that loses an electron and has a positive charge

Question 14

What is an anion?

Answer 14

an atom that gains an electron and has a negative charge

Question 15

What is the main driver of microbes?

Answer 15

pH

Question 16

What is an ion?

Answer 16

• an atom or group of atoms that has a positive or negative charge

Question 17

What are ionic bonds?

Answer 17

result from the attraction between ions of opposite charges

Question 18

How do ionic bonds form?

Answer 18

• anions and cations can form ionic bonds to neutralize their charges
• attraction holds the ions together to form a compound (eg. NaCl)

Question 19

What are covalent bonds? (2)

Answer 19

• form when atoms share pairs of electrons
• found in many compounds, especially those that contain carbon

Question 20

What are characteristics of covalent bonds? (2)

Answer 20

• very strong
• carbon atoms can form up to 4 covalent bonds

Question 21

What are hydrogen bonds?

Answer 21

Occur between covalently bonded molecules that display polarity

Question 22

How to hydrogen bonds form? (4)

Answer 22

1. when hydrogens are bonded to oxygen (example is water), the larger oxygen atom tends to pull electrons closer to itself
2. This creates a region with partial negative charge (oxy)
3. and a region with partial positive charge (H)
4. These regions can now participate in Hydrogen bonding

Question 23

What are nonpolar solvents (not in notes)?

Answer 23

• charges are more balanced/similar
• ie. benzene, and then u cant dissolve benzene and salt tgt

Question 24

What instances does hydrogen bonding cause? (2)

Answer 24

• Loose attraction between oppositely charged regions of different molecules
• serve to bridge molecules together
  Ex. in water, the hydrogen of one molecule is attracted to the O of the other molecule