Lecture 2 Flashcards
each is an individual type of atom
element
nucleus contains
- protons and neutrons
- most of the atomic mass
located outside the nucleus
electrons
charge of protons
+1
charge of neutrons
0
charge of electrons
-1
for an atom to be electrically neutral
number of protons have to equal number of electrons
ions:
atoms or molecules with a net positive or negative charge
some atoms tend to
lose or gain electrons
ionic bonds:
an electrostatic attraction between opp. charged ions
covalent bonds:
occur when atoms share electrons
carbon can participate in how many covalent bonds
4
the two types of covalent bonds
nonpolar and polar
what determines if a covalent bond is polar or nonpolar
electronegativity
electronegativity:
- describes how strongly an atom attracts electrons
- varies from atom to atom
if EN between atoms is similar
nonpolar covalent bond (=sharing)
if EN between atoms is different enough
polar covalent bond (non sharing)
nonpolar
electrons are equally shared
polar
electrons are not equally shared
if EN between atoms is greater than or equal to 0.5
polar
if EN between atoms is less than 0.5
nonpolar
building blocks of life
atoms
bigger than single atoms
macromolecules
bigger than macromolecules
viruses
bigger than viruses
prokaryotic cells
bigger than prokaryotic cells
eukaryotic cells
