Chapter 2 Flashcards
required by an organism in only minute qualities
Trace elements
smallest unit of matter that still retains the properties of an element
Atom
where protons and neutrons are packed tightly together
Atomic Nucleus
number of protons
Atomic Number
total number of protons and neutrons in the nucleus of an atom
Mass Number
different atomic forms of the same element
Isotopes
Which is the most common isotope?
carbon-12
loss of subatomic particles
Decay
C-12 and C-13 are _____ isotopes?
stable
one in which the nucleus decays simultaneously, giving off particles and energy
Radioactive Isotope
change in the number of protons, it transforms the atom to an atom of a different element
What happens when radioactive decay occurs?
Radioactive tracers are…
important diagnostic tools in medicine
Only _________ are involved in the chemical reactions between atoms
electrons
the capacity to cause change by doing work
Energy
the energy that matter possesses because of its location or structure
Potential Energy
The third electron has the least or most energy?
most
electrons on the outermost shell
Valence Electrons
outermost electron shell
Valence Shell
Elements with full valence shells are chemically….
unreactive
What are the elements with full valence shells?
helium
neon
argon
What are the strongest kinds of covalent bonds?
Ionic covalent
Sigma covalent
the sharing of a pair of valence electrons by two atoms
Covalent Bond
two or more atoms held together by covalent bonds
Molecule
when atoms share two pairs of valence electrons
Double Bond
a combination of two or more different elements
Compound
the attraction of a particular atom for the electrons of a covalent bond
Electronegativity
a covalent bond between two atoms of the same element, the electrons are shared equally because the two atoms have the same electronegativity
Nonpolar Covalent Bond
when atoms of the same element are bonded to a more electronegative atom, the electrons of the bond are not shared equally
Polar Covalent Bond
______ is one of the most electronegative elements
oxygen
two resulting oppositely charged atoms or molecules
Ions
when cations and anions attract each other
Ionic Bond
________ and ___________ interactions are crucial to life
hydrogen and vanderwaals
noncovalent attraction between a hydrogen and an electronegative atom
Hydrogen Bond
In living things, electronegative partners are usually…..
oxygen and nitrogen atoms
ever changing regions of positive and negative charge that enable all atoms and molecules to stick to one another
Van der Waals Interaction
A molecule consisting of two atoms is always ….
linear
A water molecule is shaped like a
V
A methane molecule has a geometric shape of a
tetrahedron
it determines how biological molecules recognize and respond to one another with specificality
Why is molecular shape crucial to biology?
the making and breaking of chemical bonds, leading to changes in the composition of matter
Chemical Reactions
Matter is conserved in a chemical reaction
reactions cannot create or destroy atoms but can only rearrange the electrons among them
cohesive behavior
ability to moderate temperature
expansion upon freezing
versatility as a solvent
Four Emergent Properties of Water
Cohesion
the hydrogen bonds that hold water together
the clinging of one substance to another
Adhesion
a measure of how difficult it is to stretch or break the surface of a liquid
Surface Tension
The specific heat of water is measured in
1 calorie per degree celsius
( 1 cal/g C)
PH decreases as __ increases
H+
Basic solutions are above…
7
Most biological fluids are between
6 and 8
Elements most essential to life
Carbon
Hydrogen
Nitrogen
Oxygen
Phosphorus
Sulfur
the average mass number of all isotopes of a given element
Atomic Mass
The chemical behavior of an atom is determined by the number of ________ in its outermost shell
electrons
the bonding capacity of an atom
Valence
An _______ force holds atoms together within a molecule
intramolecular
An _____ force exists between different molecules
intermolecular
bond that holds the O and H atoms within a water molecule
polar covalent
bond thats found between the partial charges of different water molecules
hydrogen bond
The innermost electron shell of an atom can hold up to __ electrons
2
Which of these relationships is true of an uncharged atom?
the number of protons is equal to the number of electrons
What determines the types of chemical reactions that an atom participates in?
the number of electrons in the outermost electron shell
Prokaryotic cells are found in the domains
bacteria and archaea
A human is classified in domain_____ and kingdom______
eukarya
animalia
A rose bush is classified in the domain _____ and kingdom _____
eukarya
plantae
Which domain includes unicellular organisms?
archaea
Fungi are classified into which domain
Eukarya
There is ___ eukaryotic domain
one
The unequal sharing of electrons within a water molecule makes the water molecule
polar
The tendency of an atom to pull electrons toward itself is referred to as its
electronegativity
In this molecule, what type of bond is found between the oxygen and the hydrogens?
polar covalent
Which one of these bonds is the weakest?
d- the hydrogen bond
Mass of 1 amu
neutron
proton
Mass 1/2000 amu
electron
Why is the increasing amount of carbon dioxide being taken up by oceans a cause for concern?
More carbon dioxide causes an increase in carbonic acid which leads to a decrease in the concentration of a carbonate ion
The number of protons in an uncharged atom
equals the number of electrons
Isotopes of an element will always differ in
atomic mass
A covalent bond will be polar if
one of the atoms sharing electrons is more electronegative
Hydrophillic substances, but not hydrophobic substances
have charges or partial charges to which water molecules can adhere
Ionic bonds form as a result of
attraction between ions that have opposite charges
Which of the following has a negligible mass?
electron
How many electrons would be present in the valence shell of a sulfur atom ( atomic number 16, mass number 32)
six electrons
A solution of pH 6 contains _______ than the same amount of solution at pH 8
100 times more H+
An atom that normally has _______ in its outer shell would not form chemical bonds with other atoms
eight electrons
Sweat has a cooling effect because of water’s high
heat of vaporization
There are ______ naturally occurring elements
92
An acid is
a substance that donates hydrogen ions to a solution
Which of the following is a trace element?
copper
This depicts
A covalent bond
Bonds between hydrogen and oxygen are called
polar covalent bonds
A water molecule is…
polar
Water molecules attached to each other are bonded by
hydrogen bonds
Each water molecule can attach to ____ other water molecules
four
high capacity to store heat
high boiling heat
surface tension
Characteristics of water
pH scale expresses…
the concentration of hydrogen ions in a solution
an _____ is any substance that increases the hydrogen ion ( H+) concentration of a solution
acid
a ____ is any substance that reduces the hydrogen ion concentration
base
