Chemical Context of Life Flashcards
Atom
basic unit of matter; made of smaller subatomic particles
Subatomic particles that make up an atom
Protons, neutrons, electrons
What makes up an atom?
Nucleus, electrons, protons, neutrons, empty space, electron shells, valence shell, electron cloud
Proton
Positively charged particles
Neutron
Particles with no charge
What makes up the nucleus of an atom
Protons and neutrons
What is the charge of an atom (USUALLY)
neutral
Strong nuclear force
force that holds the protons and neutrons in the nucleus of an atom together
What takes up 99% of the mass of an atom?
nucleus
Where is the nucleus of an atom located?
center of an atom
How do you measure the mass of the nucleus of an atom?
With atomic mass units (A.M.U) or daltons
One proton is equal to…
1 AMU (or dalton)
Electron
Negatively charged particle with 1/1840 mass of a proton. Electrons are in constant motion in the space surrounding the nucleus because they are attracted to the positive charge of the protons but do not bond with them because of their fast motion.
There are ____ amount of protons and neutrons in the nucleus of an atom.
an equal (usually)
What is the charge of an (most) atom?
Neutral because they have an even amount of electrons and protons.
Electron Cloud
the space in which the electrons revolve around the nucleus
Valence Shell
Outermost shell of an atom; contains valence electrons
Electron shell vs Electron Cloud
Electron Shell - used to visualize where electrons are, and how many are on each level
Electron Clod - describes location and energy of electrons
Element
pure substance that consists entirely of one type of atom that cannot be broken down by simple chemical means
More than ___ elements are known but only about ____ are commonly found in living organisms
100; 24
How are elements written?
One or two letter symbols (Na, H)
Atomic Number
amount of protons in the nucleus; written bottom left
Isotope
Elements with differing amounts of neutrons (Carbon-6, Carbon-7,etc.)
(Elements can be isotopes of one another)
Mass number
total amount of protons and neutrons (written top left)
How are isotopes identified?
by their mass number
Atomic mass
Average mass of all of the isotopes of a given element
96% of living matter is made of __ elements:
4; nitrogen, oxygen, carbon, and hydrogen
Radioactive Isotope
Isotopes that have a radioactive nuclei, which decays spontaneously because they have a very different amount of neutrons from the original amount which can lead to a change in the number of protons and subsequently the identity
Uses of radioactive isotopes
Can be dangerous, but also used to treat cancer, determine the age of rocks and fossils, kill bacteria, etc.
Compound
a substance formed by the chemical combination of two or more elements, in the same (never changes) proportions (can be ionic bonded or covalently bonded)
Chemical Formula
shows the composition of compounds (H20, NaCl)
Chemical Bonds
bonds that hold the atoms in molecules/elements together. Formed with the valence electrons
Main types of Chemical Bonds
Ionic bonds and covalent bonds
Ionic Bonds
formed when one or more electrons are transferred from one atom to another.
(because one atom has too many valence electrons and needs to give away to get 8 –> gives to atom with less than 8 valence electrons)
Covalent Bonds
formed when electrons are shared by atoms.
(because both electrons need 8 valence electrons but not give any away)
Ion
positively or negatively charged atoms
molecule
the smallest unit of most compounds; formed when atoms COVALENTLY bond
Van der Waals Forces
When atoms covalently bond to form molecules there is sometimes a charge that forms, (positive or negative) because one atom might have a stronger pull on the electrons being shared than the other atom. This causes molecules to be attracted to one another (if one positive and other negative). This INTERMOLECULAR force is extremely weak.
Octet Rule
Atoms always want an outer layer of 8 valence atoms (reason for bonds)
Single Bond
2 shared electrons
Double Bond
4 shared electrons
Triple bond
6 shared electrons
Important Chemical Formulas
Glucose; Water
Water
H20
Glucose
C6H1206
Electronegativity
The relative ability of an atom IN A BOND to attract electrons to itself
Trace Elements
elements that are required by an organism in small quantities
Examples of trace elements
Fe, I, Cu
Electron Affinity
the energy change associated with adding an electron to a gaseous atom.
Matter
anything with mass/ takes up space
How many elements exist in nature
92
How can compounds be bonded
ionically or covalently
Essential Elements
elements that an organism needs to healthily live + reproduce
What are the essential elements
CHON
The essential elements are the same for all organisms
True or False
False
Why is too much of a trace element bad for an orgnism
it can be toxic for them
Mass of proton
1.7 x 10^-24g
Mass of neutron
1.7 x 10^-24g
Mass of electron
1/1840 mass of a proton
Matter
anything that has mass or takes up space
Atom
smallest unit of matter which consists of subatomic particles
What subatomic particle identifies the identity of an element
protons
Which subatomic particle determines the reactivity (chemical behavior) of an element
electrons
The amount of protons usually = the amount of what
electrons
Does the nucleus have a charge
yes positive
What are the essential elements
C H O N
Isotopes
different number of neutrons in the same element
What happens to energy when a radioactive isotope spontaneously decays
energy is released
Why do radioactive isotopes spontaneously decay
because of the large difference between the number of protons and neutrons
Subatomic particles
the things that make up an atom
Common uses of radioactive isotopes in biology
1) Radioactive Tracers
2) Radiometric Dating
Radioactive Tracers
put into “biologically active molecules” and used to track atoms which allow the tracers to be analyzed with imaging instruments when the atoms with tracers one secreted or still in body
What is the bad side of radioactive tracers
too much radioactivity can damage cells
Does hydrogen have neutrons
no
Radiometric Dating
finding the exact date that fossils were alive (good for evolution) with half life
Half Life
the time it takes for 50% of the parent isotope to decay into the daughter isotope; not affected by ANYTHING
Radiometric Dating
using half life to mathematically calculate how many years have gone by
Energy
the capacity to cause change (objects always want to have less energy because that is more stable)
Potential Energy
energy that matter possesses because of its location OR structure
Do all electrons on af atom have the same potetntial energy? explain
no the ones nearer have more (DISTANCE AKA LOCATION)
Cocentric
word to describe how the distance between the shells of an atom increase when there’s more
Inert
the non reactive noble gasses
Formula for how many electrons can fit in a shell
2n^2
where n = # of level
Electron shell
shells are js predictions of energy levels in 2D -> the ayr actually made of 3D orbitals which are diff shapes and sizes and determine where e- are found
Different orbital names
s p d f
What is the chance that you will find an electron in an orbital
90%
How many orbitals can occupy an orbital at one time
2
Which electron shell has the highest amount of potential energy and why
the first one because u have to absroeb energy to move up a level to overcome the attraction to the positive nucleus
Chemical bonds
attractions that hold atoms together
What is the strongest chemical bond
covalent
Covalent bond
sharing ve- between 2 atoms to make a MOLECULE
How are covalet bonds drawn
Lewis Dot Structures or Structural Formulas
Valence
bonding capacity of an element in a covalent bond (how many electrons an element can share)
Electronegativity
the pull of an atom on electrons
What is electronegativity caused by
the amount of ve-, the atomic radius
Atomic radius
how far the positively charged nucleus is from the negatively charged valence shell
What are the 2 types of covalent bonds
nonpolar and polar
Nonpolar covalent
no partial charges (both elements have equal pull) -> made when 2 elements are the same or between C and H or S and H
Polar Covalent
there are partial charges (elements have diff pull; one is more EN) –> made between diff elements except C and H or S and H
Ionic bond
bond bc element takes ve- away from other element bc of high EN difference
What do ionic bonds creates
ions
What are the different types of ions
cations(+) and anions(-)
The compounds formed by ionic bonds are called what
ionic compounds or salts
What shape do ionic compounds make
crystal lattice
Ionic bonds are made between what types of elements
nonmetal and metal
Why are covalent bonds stronger than ionic bonds
IN BIOLOGY!!!!! this is bc basically all of bio is in aqueous solutions and ionic compounds dissociate in aqueous solutions and its harder for molecules to break up in water
What are the strong chemical bonds
ionic and covalent
What are the weak chemical bond s
hydrogen bonds
wan der waals forces
Hydrogen bonds
when H forms a covalent bond with N O or F and creates a dipole
Why are H bonds formed
bc N O and F are all highly electronegative and H gains a positive partial charge which allows it to be attracted to another highly En element
Van der Waals forces
weak bonds that occur when atoms and molecules are close together and they form bonds because of regions of brief positive and negative charges
When are van der waals forces strong
when theres alot of them
Van der Waals forces aka
London dispersion forces
Why is molecular shape important
bc the molecular geometries are important because it determines how biological molecules recognize each other and interact
Chemical Reactions
breaking/forming of bonds which leads to a change in the composition of matter
Why is the number of reactants important
bc the # needs to be balanced for an equation to be true and its important to know the mole ratio to determine the amt of products
Reversible Reaction
reactions that are true when products -> reactions and the other way around
Chemical Equilibrium
in a reversible reaction, the point when both reactions are occurring at the same rate and the concentrations of everything are relatively the same (particular ratio)
Reversible reaction symbol
⇌
Molecules are made by what type(s) of bond
covalent
Compounds are made by what type(s) of bond
ionic or covalent
Compound
2 diff or same atoms in a fixed ratio
Diatomic molecules are not compounds true or false
false
molecules ____ (are/not always) compounds, compounds (are/not always) _____
are; not always
Column on periodic table is called
l is vertical
groups or families
Row on periodic table is called
period
families are together why
similar reactivity bc same ve-
peiods are together why
same amt of shells
periodic table is organized by
increasing atomic number
Vitalism vs Mechanism
the idea that before the 1900s people thought that physical sciences (chem + physics) could not equal science of the body because life was special but after the Urey Miller experiment, people have realized that the body obeys the same rules as chem and physics
