Week 4: Cellular Biology Flashcards
Element
simplest form of matter to have unique chemical properties
Atomic Number
number of protons in its nucleus
Elements arranged by atomic number
Electrolytes
mineral salts needed for nerve and muscle function
Minerals
- inorganic elements extracted from soil by plants and passed up food chain to humans; Example: Ca, P, Cl, Mg,K, etc.
- about 4% of body weight
- important for body structure ie. Ca crystals in teeth, bones, etc.
- important for body structure
Nucleus
Center of atom; made up of protons & neutrons
Protons
Single + charge; mass = 1 amu
Neutrons
No charge; mass= 1 amu
Atomic Mass
Sum of protons & neutrons; accounts for the fact that an element is a mixture of isotopes & is close to the mass of the most abundant isotope.
Eletrons
Single - charge; very little mass
Valence Electrons
orbit the most outermost shell & determine chemical bonding properties of an atom
Isotopes
varieties of an element that differ only in the number of neutrons; isotopes of an element are chemically similar because they have the same number of valence electrons
Matter
anything that occupies space and has mass
Energy
the ability to do work
96% of body is made up of these elements
4: carbon, oxygen, hydrogen, and nitrogen
Atoms
Building blocks of elements
Radioisotope
- heavy isotope
- tends to be unstable
- Decomposes to more stable isotope
Radioactivity
process of spontaneous atomic decay
Molecule
two or more like atoms combined chemically
Compound
two or more different atoms combined chemically
Atoms formed with
Chemical Bonds
How do atoms dissociate?
Breaking of chemical bonds
Electron Shells
-electrons occupy energy levels
-Electrons closest to the nucleus are most strongly attracted
-Each shell has distinct properties:
The number of electrons has an upper limit
Shells closest to the nucleus fill first
Which electrons are involved in bonding?
- Bonding involves interactions between electrons in the outer shell (valence shell)
- Full valence shells do not form bonds
Inert Elements
Atoms are stable (inert) when the outermost shell is complete
Electron Shell Capacity
Shell 1 can hold a maximum of 2 electrons
Shell 2 can hold a maximum of 8 electrons
Shell 3 can hold a maximum of 18 electrons
Rule of Eights
Atoms are considered stable when their outermost orbital has 8 electrons
The exception to this rule of eights is Shell 1, which can only hold 2 electrons
How atoms reach stable state ?
Atoms will gain, lose, or share electrons to complete their outermost orbitals and reach a stable state
Chemically inert element exampls
Hydrogen: 2 electrons; Neon= 10 electrons (2 in the inner shell, 8 in the second electron shell)
Reactive Elements
-Valence Shells are not full and are unstable
Tend to gain, lose, or share electrons
Allow for bond formation, which produces stable valence
Types of bonds
1.ionic
2. covalent
3.hydrogen
4.
Ionic Bonds
Form when electrons are completely transferred from one atom to another
Ions
Either donate or accept electrons
Anions
Negative Charge
Cations
Positive Charge
Covalent Bonds
- Atoms become stable through shared electrons
- Single covalent bonds share one pair of electrons
- Double covalent bonds share two pairs of electrons
Single Covalent Bond Example
H2, CH4
Double Covalent Bond Example
O2
Polarity
Covalently bonded molecules
- Some are non-polar: Electrically neutral as a molecule
- Some are polar: Have a positive and negative side
Non-polar bond examples
CO2
Polar bond examples
H20
Hydrogen Bonds
- Weak chemical bonds
- Hydrogen is attracted to the negative portion of polar molecule
- Provides attraction between molecules
Synthesis Reaction
A+B => AB
- Atoms or molecules combine
- Energy is absorbed for bond formation
Decomposition reaction
AB->A + B
- Molecule is broken down
- Chemical energy is released
Synthesis Reaction example
Amino acids -> protein molecule
Decomposition Reaction
Glycogen-> glucose units
Exchange Reaction
AB + C–> AC + B
- Involves both synthesis and decomposition reactions
- Switch is made between molecule parts and different molecules are made
Exchange Reaction Example
Glucose + ATP –> Glucose Phosphate + ADP
Organic Compounds
Contain carbon
Most are covalently bonded
Example: C6H12O6 (glucose)
Inorganic compounds
Lack carbon
Tend to be simpler compounds
Example: H2O (water)
Water Vital Properties
- High heat capacity
- Polarity/solvent properties
- Chemical reactivity
- Cushioning
**Most abundant inorganic compound
Salts
- Easily dissociate into ions in the presence of water
- Vital to many body functions
- Include electrolytes which conduct electrical currents
Acids
- Release hydrogen ions (H+)
- Are proton donors
Bases
- Release hydroxyl ions (OH–)
- Are proton acceptors
Neutralization reaction
Acids and bases react to form water and a salt
pH
Measures relative concentration of hydrogen ions
pH 7 = neutral
pH below 7 = acidic
pH above 7 = basic
Buffers
chemicals that can regulate pH change
