Lecture 1 Flashcards
atomic number =?
mass number =?
atomic number = ##protons
mass number = #protons - #neutrons
number of protons = the number of electrons
what are compounds?
compounds are molecules composed of different elements ( two molecules or more)
what are valence electrons?
The number of electrons needed to complete / fill up the outermost orbital ( the valence shell )
- 8 valence electrons is the ideal number to have a complete orbit
what are chemical bonds and describe two types of interactions
chemical bonds are interactions between atoms and molecules
1) interactions between atoms
(covalent bonding)
2) interactions between molecules (hydrogen bonding, like DNA)
what is the main goal of strong bonds? name two types of strong bonds
strong bonds= chemical bonds that are used to complete the outer shell (valence shell), involves giving and acquiring electrons
1) covalent bonds ( sharing of electrons)
2) ionic bonds (transfer of electrons)
What does polarity depend on?
electronegativity - increases across and up a periodic table ( measure of an atoms attraction for shared electrons in covalent bonds ) - the more electronegative an atom is, the more it pulls the electrons towards itself.
What are nonpolar covalent bonds? and give an example
non polar covalent bonds are bonds between two atoms that have similar electronegativities - electrons are shared equally between them
- lipids are primarily non polar as they consist of hydrogen and carbon covalent bonds ( think of / look up the three fatty acids)
what are polar covalent bonds? and give an example
polar covalent bonds are bonds between two atoms that have different electronegativities. The atoms with the higher electronegativity will pull the electrons towards its self stronger.
- two opposite charged atoms
ex: water; the oxygen in water is very electronegative creating poles
What are ionic bonds?
electrons > # protons = -ve
ionic bonds involves the complete transfer of electrons causing the formation of ions
# electrons < # protons = +ve
placing ionic bonds in water weakens the bonds
what is the difference between a cation and an anion?
Cation= a positively charged ion
Anion= a negatively charged ion
Name two roles that ions play in our bodies
1) Neuronal actions potential
2) Muscle contraction
Summary of non polar, polar and ionic bonds
Nonpolar covalent bonding= electrons shared equally
Polar covalent bonding = electrons shared unequally
Ionic bonding = electrons are transferred
Properties of weak chemical bonds?
- allows molecules to interact
- adhering molecules briefly when they collide with eachother
- provides stability within large molecules
what are the three types of chemical bonds?
1)Hydrogen bonding
2)van der waals interactions
3)Ionic bonds in water
what are hydrogen bonds?
hydrogen bonds are weak bonds that form between an atoms that has a partial negative charge and a hydrogen atoms that is covalently bonded to a very electronegative element ( i.e. oxygen or nitrogen )
why are hydrogen bonds so important for living organisms?
provides high occurance/presence of water molecules in our cells and tissues
what are van der waals interactions?
where does it occur in biology?
the interactions of adjacent atoms coming close together that their outer electron clouds just barely touch.
The interactions between stacked bases of DNA, keep DNA structure=Gecko
what is trace element?
a small amount of that element that is present in living organisms
