Module 1.2: Chemical Bonds Flashcards
What is a chemical bond?
The force holding atoms together to form molecules or compounds
What does a molecule consist of?
the same or different elements
what does a compound consist of?
different elements
when are chemical bonds created?
when atoms share, donate, or receive electrons to achieve a stable electron configuration
what are the three types of chemical bonds?
- Ionic Bonds (results from gaining or losing of electrons)
- Covalent Bonds (results from sharing electrons)
- Hydrogen Bonds (occurs from attraction of oppositely charged molecules)
describe ionic bonds
- Opposite charged ions attract each other
- One atom donates electrons to another, creating oppositely charged ions that attract each other
- creates cation and anion
where are ionic bonds found in the body?
tissues and electrolytes
what do ionic bonds give strength to?
teeth and bones (hydroxyapatite=made up of ionic bonds)
Are ionic bonds common in the body? Why or why not?
No they are not common because most ions remain stable in the body’s watery fluid (body is made up of 60% water)
what is an electrolyte?
A substance that breaks up into positive and negative ions when it is dissolved in water or body fluids
what are electrolytes important for?
Important in regulating nerve and muscle function, hydration, balance blood pH, blood pressure
describe covalent bonds
- Strongest and most common form of chemical bond in living organisms
- Bonds form when a pair of electrons is shared between two elements
what element is the basis for organic chemistry and why?
carbon because it can share its 4 outer electrons with multiple elements creating complex
structures
what is the correlation between strength of covalent bonds and the amount of bonds formed?
↑ # electron pairs shared = stronger
covalent bond
when are double covalent bonds common?
in molecules where atoms need more than one pair of electrons to complete their outer shells (i.e. oxygen)
what is a polar covalent bond?
Type of covalent bond where electrons are shared unequally between two atoms
describe electronegativity in polar covalent bonds
- 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
what do polar covalent bonds create?
a dipole (A bond has partial charge on each end)
explain polar covalent bonds using H2O as an example
- 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
describe a hydrogen bond
- Weak bond formed between a hydrogen atom, already covalently bonded to a highly electronegative atom (like oxygen or nitrogen), and another electronegative atom.
how do electrons behave in a hydrogen bond?
Defined more as an attraction, not sharing or
transferring electrons
what are hydrogen bonds useful for?
Useful in linking molecules like large 3-D molecules
what features do hydrogen bonds provide water?
- Cohesion
- Surface Tension
-bonds are weak in water but theres a lot of them
what is needed in the lungs to expand? why?
surfactant
* Lungs are lined with fluid (water)
* High surface tension contracts the lungs so we need surfactant to help expand
where is surfactant produced? What is it made of?
by the lung (type II alveolar cells)
* Mix of phospholipids and lipoproteins
how does surfactant work?
- Reduces surface tension in the alveoli,
preventing them from collapsing during
exhalation. - It goes between O-H bonds in water to
reduce surface tension
what is the risk with surfactant in premature babies?
- Infants born before 34 weeks gestation
often lack sufficient surfactant, leading to
respiratory distress syndrome (RDS) - May require surfactant therapy
define a chemical reaction
Breaking and/or forming of chemical bonds where substances (i.e. reactants) are transformed into new substances (i.e. products)
what are the key features of a chemical reaction?
- Rearranging atoms of reactants to form products
- Energy Changes, resulting in energy release (exergonic) or energy absorption (endergonic)
what is chemical potential energy?
energy stored in the chemical bonds of substances released during chemical
reactions
total energy in chemical reactions follows which law?
first law of thermodynamics: Energy cannot be created or destroyed, only transformed or transferred from one form to another
total energy is BLANK though it may BLANK BLANK
constant, change forms
definition and example of an exergonic reaction
- Release more energy than absorbed
- Example: Glucose breakdown into usable
energy (ATP)
definition and example of endergonic reaction
- Absorb more energy than
released - Example: Photosynthesis
define metabolism
Sum of all chemical reactions that occur within an organism to sustain life
what does metabolism do?
Provide energy to maintain body functions
what does metabolism combine? how?
Combines exergonic and endergonic reactions
* Energy released from exergonic reactions contributes to energy required for endergonic reactions to occur
what is catabolism? an example? exergonic or endergonic?
- Breakdown of larger molecules into smaller ones
-Releases energy (often stored as ATP)
-Example: Breakdown of carbohydrates into glucose
exergonic
what is anabolism? an example? exergonic or endergonic?
-Building larger molecules from smaller ones
-Requires energy input for synthesis
-Example: Synthesis of proteins from amino acids
endergonic
sometimes, chemical reactions are BLANK
reversable
what is an example of a reversable chemical reaction? what is this important for in humans?
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
what is an enzyme?
Substances that speed up chemical reactions by lowering the energy required for it to occur
why are enzymes essential?
normal body temperature and reactant
concentrations are too low to cause chemical reactions to occur quickly enough
enzymes remain BLANK and can be used BLANK
unchanged, repeatedly
enzymes are…
catalysts in living cells and highly specific to the
substrate they react to
what are enzymes regulated by?
various cellular controls in the body to make sure we have enough
many BLANK are BLANK
vitamins, coenzymes
what is a coenzyme?
organic, reusable molecules that assist enzymes
what is an example of a coenzyme?
Niacin (B3) is important coenzyme NAD
* involved in carbohydrate metabolism
what does the pH scale measure?
the amount of hydrogen ions present (more H+, more acidic)
what is meant by the pH is a negative scale?
Numbers go down, H+ concentration goes up
what is meant by the pH is a log scale?
Difference between pH of 4 and 5 is 10x; therefore pH 4 has 10x more H+ ions than pH 5
what is neutral on the pH scale?
7
what is the most acidic thing in the human body?
gastric juice at 2 or 3 pH
what is the pH of saliva
slightly acidic
what is the pH of blood
neutral around 7.35-7.45
what is the pH of urine
ranges based on person to compensate for changes in blood pH, but generally 5-8pH
what does being below 7.35pH in blood mean?
physiological acidosis
what does being above 7.45pH in blood mean?
physiological alkalosis
