BIOCHEMISTRY QUIZ REVIEW Flashcards
What are atoms?
Atoms are defined as the smallest unit of matter that forms a chemical element.
What are atoms composed of?
They are composed of subatomic particles. The nucleus of an atom contains protons and neutrons. The shells contain electrons.
Maximum number of electrons in shell order
2, 8, 8, 18, 18, 32,32
What are elements? + Examples
Substance that contains only one type of atom. Silver, Gold, Sodium
Atomic number represents
Number of protons or electrons
Atomic mass
Average weight of an atom. Atomic number (protons) subtract atomic mass is neutrons
Can individual atoms’ mass vary?
Yes. For an example Carbon can all have different mass. The mass listed on periodic tables are just the average weights.
What are isotopes?
Elements that have the same number of protons but different number of neutrons.
If isotopes are unstable and produce radiation, what are they called?
They are called radioactive.
What are compounds?
When two or more elements are combined by covalent or ionic bonding
Examples of compounds?
NaCl (salt), KI (Potassium Iodide)
What is Ionic bonding? (4)
- Forms between metal and non-mentals.
- Elements will lose or gain electrons.
- Metals lose electrons while non-metals gain electrons
- TRANSFER of electrons occurs.
What is covalent bonding? (4)
- Forms between two non-metals.
- Bond forms from molecules.
- Atoms do not become charged.
- SHARING of electrons occurs.
What are acids?
Compounds that dissociate (break apart) in water and release Hydrogen ions. Ex. HCl
What are bases?
Compounds that dissociate in water and release Hydroxide ions. Ex. NaOH
What is a pH?
Quantitative measure of how acidic or basic a solution is
How does the pH scale work?
Scale ranges from 0 to 14. Lower the number the more acidic; lower than 7 is acidic. Higher the number the more basic. pH of 7 is neutral.
What are buffers?
To keep pH levels from changing, cells contain BUFFERS. It is a chemical that can take excess hydrogen ions or excess hydroxide ions.
What are common buffers?
Acetic acid & Carbonic acid-bicarbonate.
Inorganic compounds (3)
- Ionic bonding (mostly) so metal and non-metal.
- Smaller number of atoms
- Associated with non-living elements.
Organic compounds
- Covalent bonding (always) so non-metal and non-metal.
- Larger number of atoms
- Associated with living elements.
What type of bond is water?
Water is linked through covalent bonds but hydrogen bonds are formed
What is a polar molecule?
Molecule that is slightly positive and slightly negative.
Why is water polar?
They have an uneven distribution of electrons
Because water is polar, what type of bonds do water form?
Hydrogen bonds
How do hydrogen bonds occur?
When a partial positive hydrogen is attracted to a partial negative oxygen.
Are hydrogen bonds strong?
No. It is represented by a dotted line because it can be easily broken.
How is hydrogen bonding liquid at room temperature?
It has a low freezing point and a high boiling point allowing it to be liquid at room temperature.
How do oceans remain at a constant temperature, hydrogen bond?
Water has a high heat capacity. It absorbs heat quickly and warms up and releases heat slowly before freezing
Water is a universal _____
Universal solvent. It dissolves solutes and dissociates substances.
6 functions of water in the human body
- Transportation of nutrients and waste in blood and tissues.
- Main component of all cells.
- Controls body temperature – when you’re too hot, you sweat.
- Breaks down large molecules to small molecules (Hydrolysis)
- Lubricant – Tears, mucus, saliva.
- Universal Solvent
How are all atoms electrically neutral?
They contain equal amounts of protons and electrons.
How is it possible for carbon to have different masses yet still be carbon? What part of an atom determines the characteristics?
The atomic mass on the periodic table is just the average. The mass can always vary per atom but what makes an atom is their atomic number. The number of protons is also a part of their identity as well.
Which part of the subatomic particle in an atom create chemical reactions?
The Electrons. Because it is on the outer shell, they have low ionization energy and can participate in chemical reactions.
What is an octet rule? what’s the exception
8 electrons in outer shell. Exception is that shell 1 only has 2 electrons.
How does an ionic bond form?
Metal transfers electrons to a non-metal
What is an ion?
positively or negatively charged particle
How does an atom acquire a positive charge?
Atom loses an electron
How does an atom acquire a negative charge?
When they gain electrons.
What type of elements react in ionic bonding?
Non-metal + metal.
Why do ionic compounds form crystals?
Because no atom donates an electron to Cl atom
What type of atoms form covalent bonds?
When pairs of electrons are shared by atoms; non-metal + non-metal.
How is ionic bonding different from covalent bonding?
Electrons are shared, not transferred.
What is a Lewis Dot Diagram?
Diagram that shows the number of electrons in the outermost shell.
How many electrons are shared to form a double bond?
2.
4 Important inorganic compounds
Water, salts, acids, bases.
What type of bonding holds water molecules together?
Covalent bonds because they are non-metals.
How are partial charges indicated?
The s+ and s- sign thing
What is an electronegative atom?
Atom which presents more of negatively charged distribution
Why does a hydrogen bond form?
H (partial) is attracted to O (partial). A weak bond will form
Hydrophilic
Water loving
Hydrophobic
Water hating
Why is the fact that water can dissolve so many things important?
Molecules can be transported in our blood cells and they are small enough to diffuse into cells.
If you live in an area that has large amounts of water, the area will never get too hot or cold. Why?
Water has a higher heat capacity than land, so it can absorb more heat before warming up. It also releases heat as it cools.
Why is it advantageous for the body to have such a large volume of water?
Good for flushing bacteria as well as keeping our body temperature constant.
Why is it advantageous for water to expand when freezing top to bottom for organisms?
Solid water is less dense due to hydrogen bonding. Ice layers and helps protect organisms below (insulation)
How does water behave with such high surface tension?
It has stronger molecular interaction. Stronger the cohesive tension = stronger surface tension.
Why does water rise in the glass tubes but not in plastic tubes?
Caused by forces of attraction between molecules of water and glass walls.
Why does a plastic tube not form a meniscus?
Plastic is chemically similar to oil and not charged so it has a tendency to repeal water when In contact.
What does it mean when a molecule has dissociated?
Molecule splits up and ions are formed
Define acid
H+ present, reacts with bases
How does Hydrochloric acid dissociate and why is it strong?
Strong because it dissociates almost completely. HCl -> H+ + Cl-
Define base
OH- present
How is salt formed?
Formed in a reaction between an acid and a base
What is the range of the pH scale?
0-14
Which pH is neutral?
7
Describe a neutral solution
A chemical solution which is neither acidic or basic, and rather equal
Acidic scale
0-6
Basic scale
8-14
How does hydrogen change when pH value decreases by one
The Hydrogen concentration increases by a power of 10
Why is pH important for biology?
Maintains structure and activity of macromolecules Organisms need to maintain a certain level of pH to keep enzymes in state.
What is a buffer?
A buffer is a chemical that can take up excess hydrogen or excess hydroxide to keep pH constant.
What do organic compounds always contain?
Carbon
Synthesis
Production of chemical compounds from simpler materials.
Hydrolysis
Breakdown of compounds due to reaction with water.
What is the reaction of salt being formed called?
Neutralization reaction
How does hydrogen change when pH value decreases by 2
Hydrogen concentration increases by a power of 100
