Module 1.2: Chemical Bonds

Question 1

What is a chemical bond?

Answer 1

The force holding atoms together to form molecules or compounds

Question 2

What does a molecule consist of?

Answer 2

the same or different elements

Question 3

what does a compound consist of?

Answer 3

different elements

Question 4

when are chemical bonds created?

Answer 4

when atoms share, donate, or receive electrons to achieve a stable electron configuration

Question 5

what are the three types of chemical bonds?

Answer 5

• Ionic Bonds (results from gaining or losing of electrons)
• Covalent Bonds (results from sharing electrons)
• Hydrogen Bonds (occurs from attraction of oppositely charged molecules)

Question 6

describe ionic bonds

Answer 6

• Opposite charged ions attract each other
• One atom donates electrons to another, creating oppositely charged ions that attract each other
• creates cation and anion

Question 7

where are ionic bonds found in the body?

Answer 7

tissues and electrolytes

Question 8

what do ionic bonds give strength to?

Answer 8

teeth and bones (hydroxyapatite=made up of ionic bonds)

Question 9

Are ionic bonds common in the body? Why or why not?

Answer 9

No they are not common because most ions remain stable in the body’s watery fluid (body is made up of 60% water)

Question 10

what is an electrolyte?

Answer 10

A substance that breaks up into positive and negative ions when it is dissolved in water or body fluids

Question 11

what are electrolytes important for?

Answer 11

Important in regulating nerve and muscle function, hydration, balance blood pH, blood pressure

Question 12

describe covalent bonds

Answer 12

• Strongest and most common form of chemical bond in living organisms
• Bonds form when a pair of electrons is shared between two elements

Question 13

what element is the basis for organic chemistry and why?

Answer 13

carbon because it can share its 4 outer electrons with multiple elements creating complex
structures

Question 14

what is the correlation between strength of covalent bonds and the amount of bonds formed?

Answer 14

↑ # electron pairs shared = stronger
covalent bond

Question 15

when are double covalent bonds common?

Answer 15

in molecules where atoms need more than one pair of electrons to complete their outer shells (i.e. oxygen)

Question 16

what is a polar covalent bond?

Answer 16

Type of covalent bond where electrons are shared unequally between two atoms

Question 17

describe electronegativity in polar covalent bonds

Answer 17

• One atom has a stronger attraction for the shared electrons (higher electronegativity) than the other
• Atom with stronger pull on electrons → slightly –ve
• Atom with weaker pull on electrons → slightly +ve

Question 18

what do polar covalent bonds create?

Answer 18

a dipole (A bond has partial charge on each end)

Question 19

explain polar covalent bonds using H2O as an example

Answer 19

• In a water molecule, the bond between oxygen and hydrogen is polar
• Oxygen is more electronegative (δ-), pulling
  electrons closer to itself
• This causes hydrogen to become more
  electropositive (δ+)
• This bond gives water its unique ability to dissolve many substances

Question 20

describe a hydrogen bond

Answer 20

• Weak bond formed between a hydrogen atom, already covalently bonded to a highly electronegative atom (like oxygen or nitrogen), and another electronegative atom.

Question 21

how do electrons behave in a hydrogen bond?

Answer 21

Defined more as an attraction, not sharing or
transferring electrons

Question 22

what are hydrogen bonds useful for?

Answer 22

Useful in linking molecules like large 3-D molecules

Question 23

what features do hydrogen bonds provide water?

Answer 23

• Cohesion
• Surface Tension
  -bonds are weak in water but theres a lot of them

Question 24

what is needed in the lungs to expand? why?

Answer 24

surfactant
* Lungs are lined with fluid (water)
* High surface tension contracts the lungs so we need surfactant to help expand

Question 25

where is surfactant produced? What is it made of?

Answer 25

by the lung (type II alveolar cells) * Mix of phospholipids and lipoproteins

Question 26

how does surfactant work?

Answer 26

* Reduces surface tension in the alveoli, preventing them from collapsing during exhalation. * It goes between O-H bonds in water to reduce surface tension

Question 27

what is the risk with surfactant in premature babies?

Answer 27

* Infants born before 34 weeks gestation often lack sufficient surfactant, leading to respiratory distress syndrome (RDS) * May require surfactant therapy

Question 28

define a chemical reaction

Answer 28

Breaking and/or forming of chemical bonds where substances (i.e. reactants) are transformed into new substances (i.e. products)

Question 29

what are the key features of a chemical reaction?

Answer 29

* Rearranging atoms of reactants to form products * Energy Changes, resulting in energy release (exergonic) or energy absorption (endergonic)

Question 30

what is chemical potential energy?

Answer 30

energy stored in the chemical bonds of substances released during chemical reactions

Question 31

total energy in chemical reactions follows which law?

Answer 31

first law of thermodynamics: Energy cannot be created or destroyed, only transformed or transferred from one form to another

Question 32

total energy is BLANK though it may BLANK BLANK

Answer 32

constant, change forms

Question 33

definition and example of an exergonic reaction

Answer 33

* Release more energy than absorbed * Example: Glucose breakdown into usable energy (ATP)

Question 34

definition and example of endergonic reaction

Answer 34

* Absorb more energy than released * Example: Photosynthesis

Question 35

define metabolism

Answer 35

Sum of all chemical reactions that occur within an organism to sustain life

Question 36

what does metabolism do?

Answer 36

Provide energy to maintain body functions

Question 37

what does metabolism combine? how?

Answer 37

Combines exergonic and endergonic reactions * Energy released from exergonic reactions contributes to energy required for endergonic reactions to occur

Question 38

what is catabolism? an example? exergonic or endergonic?

Answer 38

- Breakdown of larger molecules into smaller ones -Releases energy (often stored as ATP) -Example: Breakdown of carbohydrates into glucose exergonic

Question 39

what is anabolism? an example? exergonic or endergonic?

Answer 39

-Building larger molecules from smaller ones -Requires energy input for synthesis -Example: Synthesis of proteins from amino acids endergonic

Question 40

sometimes, chemical reactions are BLANK

Answer 40

reversable

Question 41

what is an example of a reversable chemical reaction? what is this important for in humans?

Answer 41

Carbonic acid-bicarbonate buffer system * Maintain acid-base balance, regulates pH of blood and other fluids * When ↑ pH, low H+ concentration; equation shifts right * When ↓ pH, high H+ concentration; equation shift left

Question 42

what is an enzyme?

Answer 42

Substances that speed up chemical reactions by lowering the energy required for it to occur

Question 43

why are enzymes essential?

Answer 43

normal body temperature and reactant concentrations are too low to cause chemical reactions to occur quickly enough

Question 44

enzymes remain BLANK and can be used BLANK

Answer 44

unchanged, repeatedly

Question 45

enzymes are...

Answer 45

catalysts in living cells and highly specific to the substrate they react to

Question 46

what are enzymes regulated by?

Answer 46

various cellular controls in the body to make sure we have enough

Question 47

many BLANK are BLANK

Answer 47

vitamins, coenzymes

Question 48

what is a coenzyme?

Answer 48

organic, reusable molecules that assist enzymes

Question 49

what is an example of a coenzyme?

Answer 49

Niacin (B3) is important coenzyme NAD * involved in carbohydrate metabolism

Question 50

what does the pH scale measure?

Answer 50

the amount of hydrogen ions present (more H+, more acidic)

Question 51

what is meant by the pH is a negative scale?

Answer 51

Numbers go down, H+ concentration goes up

Question 52

what is meant by the pH is a log scale?

Answer 52

Difference between pH of 4 and 5 is 10x; therefore pH 4 has 10x more H+ ions than pH 5

Question 53

what is neutral on the pH scale?

Answer 53

7

Question 54

what is the most acidic thing in the human body?

Answer 54

gastric juice at 2 or 3 pH

Question 55

what is the pH of saliva

Answer 55

slightly acidic

Question 56

what is the pH of blood

Answer 56

neutral around 7.35-7.45

Question 57

what is the pH of urine

Answer 57

ranges based on person to compensate for changes in blood pH, but generally 5-8pH

Question 58

what does being below 7.35pH in blood mean?

Answer 58

physiological acidosis

Question 59

what does being above 7.45pH in blood mean?

Answer 59

physiological alkalosis