Ch. 2 - Chemical Context of Life Flashcards
matter
Takes up space and has mass. Affected by gravity
element
pure substance, can’t be broken down into different substances
elements are made up of
atoms
Trace element
we only need them in small quantities (zinc, iron)
elements of life
we need them to survive.
25 total, but 4 make up 96% of all living matter
compound
A substance consisting of two or more elements combined in a fixed ratio (H20)
four essential elements make up 96% of all living matter
a. Oxygen
b. Carbon
c. Hydrogen
d. nitrogen
If there is a deficiency of an essential element ______ happens
disease
Subatomic particles
neutron, proton, electron
neutron
neutral charge
proton
+ charge
electron
- charge
atomic number
of protons in an atom
True/False: Atoms have the same number of protons and electrons
Mostly true: when they are in their neutral state, which is their normal state
Ion
An electrically charged atom (not in neural state). It does NOT have the same number of protons and electrons
Atomic mass
Protons + neutrons = atomic mass
Isotope
same number of protons but greater number of NEUTRONS than other samples of the same element, so it has greater mass
It can spontaneously turn radioactive.
Example of isotopes
Carbon-6, Carbon-12, Carbon 14
Electron shells
represent the average distance from the nucleus and energy level of electrons circling the nucleus
The ___ an electron is to/from the nucleus, the more energy it has
a) closer
b) further
further
When an electron absorbs energy it becomes
excited
Excited electrons move to _____ energy levels
higher
When an electron loses energy
falls down energy levels towards the nucleus
energy
capacity to cause change
Potential energy
energy in matter due to location or structure
higher locations= more potential energy
more complex structures = more potential energy
Kinetic energy
energy of motion
The chemical behavior of an atom depends on
its electron configuration and distribution
Valence electrons
electrons in the outermost shell (red)
of valence electrons determines atom’s chemical behaviors (shown in periodic table groups)
Orbital
the three-dimensional space where an electron is found 90% of the time
Covalent bonds (strong)
Between non-metals; they share valence electrons
- Can be polar or non-polar
Molecule
atoms joined by covalent bonds
electronegativity
an electronegative atom pulls electrons of a covalent bond towards itself
(Polar covalent bonds)
Non-polar covalent bond
The electron is shared equally (O2, H2)
Always between atoms of the same element
Polar covalent bond
One atom is more electronegative than the other and pulls electrons towards itself
The more to —> in the periodic table, the more electronegative
Anion
negatively charged ion (stole the electron in the bond)
Cation
positively charged ion. Lost an electron
Ionic bond (strong)
Formed between anions and cations
(Na+Cl-)
Metals and non-metals
Ionic compounds almost always create
salts, made of crystals
Two types of weak bonds
1) Hydrogen bonds
2) Van der Waals interactions
Hydrogen bonds
between Hydrogen in a polar covalent bond (because the H is slightly +) and any neighboring negative charge.
Van der Waals interactions
the weakest type of bonds, temporary
Electrically charged outer shells of atoms/molecules nearby barely touch each other as they move around
Why are weak bonds important?
They give shape to large molecules and help them adhere to each other
Chemical bonds are made and broken in _______
chemical reactions that change the composition of matter
The resulting substance(s) of a chemical reaction is the _______
product (s)
Chemical reaction basic formula
reactant + reactant –> product
when the forward and reverse reaction rates are equal in a chemical reaction
Chemical equilibrium
(balanced equation)
