Bio Lecture Slides Series 2 (Chemistry of Life) Flashcards
What are the two known components of the universe?
energy and matter
Define energy.
ability to do work, no mass, no volume; neither created nor destroyed, only changes form
Define matter.
has mass and occupies volume; neither created nor destroyed, only changes form.
What does E=MC2 tell us about matter and energy?
the formula reveals that energy and matter are related
Matter can exist as a _____, _____, or _____.
solid, liquid, or gas
Matter is composed of _____.
elements.
Define element.
a substance that cannot be broken down into another substance by ordinary chemical means
How many naturally occurring elements are there?
92
How many elements make up about 98% of the body weight of most organisms?
Six, CHNOPS (Carbon, Hydrogen, Nitrogen Oxygen, Phosphorus, Sulfur)
Name the elements in CHNOPS.
Carbon, Hydrogen, Nitrogen Oxygen, Phosphorus, Sulfur
In living organisms, the top two elements present are _____ and _____.
oxygen (65%) and carbon (18%)
In living organisms, the fewest occurring elements present are _____, _____, _____, and _____.
NCPS (nitrogen, calcium, phosphorus, sulfur)
Atomic theory states that elements consist of _____.
atoms
Define atom.
the basic unit of matter
Define atomic symbol.
name of the atom or element
Name the three subatomic particles.
neutrons, protons, electrons
Describe a neutron.
no electrical charge, found in nucleus
Describe a proton.
positive charge, found in nucleus
Describe electrons.
negative charge, found outside of nucleus
Mass number is equal to the ____________.
sum of protons and neutrons – electrons have about zero mass
Atomic weight changes with _____.
gravity
All atoms of an element have the _____ number of protons.
same
The atomic number also gives number of _____ if an atom is electrically neutral.
electrons
In the periodic table, the chemical elements are arranged in order of _____ _____ _____.
increasing atomic number
In the periodic table, the rows are called _____.
periods
In the periodic table, the columns are called _____.
groups
Elements’ chemical and physical characteristics recur in a _____ manner on the periodic table.
predictable
On the periodic table, atoms are arranged in _____ and _____.
periods (rows) and groups (columns)
Variations of atoms are called _____ and _____.
ions and isotopes
Ions are __________.
atoms or small molecules that have gained or lost an electron
Isotopes are __________.
elements with same number of protons but different numbers of neutrons
Isotopes have naturally occurring variations in the number of _____.
neutrons
The imbalance between the numbers of protons vs. electrons creates the charged particle known as a(n) _____.
ion
Are isotopes stable or unstable?
unstable
Do isotopes emit radiation?
Yes, the more unstable they become and the more decay
Define half life.
The amount of time it takes for half the mass of a radioactive isotope to breakdown
Radioactive isotope behavior is essentially the same as a stable isotope of the same element. True or false?
True
Isotopes can be used as tracers in PET scans. True or false?
True
Isotopes can cause damage to cells leading to cancer. True or false?
True
Isotopes can be used to sterilize medical equipment. True or false?
True
Isotopes Can be used to date very old objects. True or false?
Can be used to date very old objects
Do electrons have much mass?
No they do not, they have a mass of 9.1 x 10-28
The electrical charge (while opposite) of an electron is _____ that of a proton.
equal to
Where are electrons found?
Electrons are found outside the nucleus (most of the atom being empty space) in energy levels called shells.
Electrons move in some fashion _____ the nucleus.
around
Changes in the nucleus of an atom are called _____ _____.
nuclear reactions (rxn)
Electrons are responsible for all chemical reactivity because __________.
they are always changing
Electrons are attracted to the __________.
positively charged nucleus
Inner shell electrons require _____ energy to stay in the atom than electrons further from the nucleus.
less
Electrons are associated with certain energy levels because __________.
electrons are attracted to the positively charged nucleus, and inner shell electrons require less energy to stay in the atom than electrons further from the nucleus.
The energy of an electron can be expressed as a _____ _____ _____.
Frequency of light. Electrons have the ability to absorb certain wavelengths or frequencies of light.
Once electrons absorb energy they jump up to a new electron shell (at a higher E level). True or false?
True.
Because _____ are limited to an energy level within the atom, they cannot hold on to this energy and fall back to their shell and give back off the E they absorbed.
electrons
This ability of electrons are important to biological processes _____ and _____ and the principle is applied to produce fluorescent lights.
photosynthesis, respiration
According to fill order, the first electron shell can hold up to _____ electrons.
2
According to fill order, the second electron shell can hold up to _____ electrons.
8
According to fill order, the third electron shell can hold up to _____ electrons.
18
According to fill order, the fourth electron shell can hold up to _____ electrons.
32
According to fill order, third and fourth shells will not fill with more than 8 electrons until all _____ electrons are available
18 or 32
Outer shell electrons called _____ _____ electrons and are responsible for chemical reactivity
valence shell
A molecule is _____ or more atoms bonded together.
2
Compounds contain more than one type of atom bonded together. True or false?
True
Define Octet Rule.
All shells except the first are satisfied at 8 e- and bond to attain this more stable configuration.
Name the three types of chemical bonding.
ionic, covalent, metallic
An e- transfer that creates ions, one positive and one negative, and this electrostatic force holds the atoms together. It also occurs between metals and nonmetals and is called _____ bonding.
ionic bonding
How does sodium behave in an ionic bond?
Sodium has 1 electron in valence shell and usually gives up an electron
How does chlorine behave in an ionic bond?
Chlorine has 7 electrons in valence shell and usually accepts an electron from another atom
Covalent bonding is essentially electron _____.
sharing
In this type of bonding, each atom contributes one electron to make a pair and the force of attraction of each nuclei for this pair holds the atoms together in a bond.
covalent bonding
Covalent bonds occur between two or more _____.
nonmetals, and more than one pair can be shared
In covalent bonds, all molecules do not share equally – the greater the center of positive charge (nucleus) the more it can draw electrons in closer. True or false?
true
Define polar covalent bond.
Two atoms are bonded and their nucleus contains different numbers of protons. All bonds except two of the same atoms are polar bonds.
Picture 2 hydrogen atoms covalently bonded and sharing electrons to fill their first shell. How is this possible?
orbitals overlap
Covalently bonded atoms may also share more than one pair of electrons, true or false?
True. A double bond = 2 pairs of e- shared. •A triple bond = 3 pairs of e- are shared.
In which type of bond might a single atom form bonds with more than one atom?
covalent bond
When atoms do not share the electrons equally this can also create molecules with an unequal distribution of charge. This is called a _____.
dipole (water is an example of a dipole)
A molecule can contain polar bonds but not be a dipole. Which gas is an example of this?
methane
Metallic bonding is essentially _____ _____.
electron pooling
Which type of bond results in none of the valence e- belong to any one nucleus but are instead shared by all the nearby nuclei; occurs between 1, 2, or more metals?
metallic bond
Which type of bond affects the properties of metals (i.e. shiny or metallic luster), the malleability of metal, and also responsible for the fact that most metals are great conductors of heat and electricity?
metallic bond
A molecule used within the biochemical pathways of cells that has lost an electron and therefore will steal an electron from the closest molecule is known as a _____ _____.
free radical
_____ _____ can set off a chain reaction resulting in cell death and even tissue damage.
Free radicals
_____ _____ _____ is the latest theory to explain aging and some disease processes like cancer.
Free radical formation
Scientist tell us the answer to free radicals are _____ any molecule that reacts with free radicals, neutralizing their ability to damage biological molecules.
antioxidants
Well documented are: Vitamins C, D, E and beta carotene are well-documented _____ _____.
Dietary antioxidants
Long term lack of vitamin _____ is associated with 15 types of cancer, including prostrate cancer in men.
D
The latest antioxidants to be discovered are a group of _____ compounds, sometimes simply called phytochemicals.
plant
Approximately 200 of phytochemical compounds have been identified to date and most are associated with _____ and _____.
fruits and vegetables
Antioxidants are also anti-carcinogenic, which means they __________.
fight or prevent cancer
In a chemical reaction, reactants are __________.
molecules that participate in reactions and are shown to the left of the arrow
In a chemical reaction, products are __________.
molecules formed by reactions and are shown to the right of the arrow
An equation is balanced when __________.
the same number of each type of atom occurs on both sides of the arrow because matter never disappears
In chemical reactions, the two-way arrow means __________.
the rxn is reversible
If a reaction is _____ it means that the initial or some of the initial reactants are regenerated at the end of the reaction so the reaction continues to occur.
cyclic
All life began in _____.
water
_____ is the single most important molecule on Earth.
water
All organisms are 70-___% water.
90
What type of bond is water?
polar covalent
Which bond is a slightly positive hydrogen of one water molecule attracted to the slightly negative oxygen in another water molecule?
hydrogen bond
Polar covalent bonds do not always result in a polar molecule, true or false?
true. (methane is an example)
In a polar covalent bond, atoms do not share _____ equally.
electrons
These properties (solvency, cohesion and adhesion, high surface tension, high heat capacity, high heat of vaporization, high heat of fusion, and varying density) all belong to which compound?
water
Water is a compound and a _____.
solvent; it dissolves many substances
Define hydrophilic.
molecules attracted to water
Define hydrophobic.
molecules not attracted to water
Water causes salt to _____.
dissociate
The ability of water molecules to cling to each other due to hydrogen bonding is called _____.
cohesion
The ability of water molecules to cling to other polar surfaces is called _____.
adhesion
Adhesion and cohesion allow water to be an excellent _____ system inside and outside of living organisms.
transport
High surface tension, how water molecules at the surface cling more tightly to each other than to the air above, is due to which bond?
hydrogen bond
The many hydrogen bonds linking water molecules together allow water to absorb heat without greatly changing its temperature. This is the reason for water’s _____ _____ _____.
High heat capacity
Temperature of water rises and falls slowly; this means that water _____ temperature.
stabilizes
The following characteristics all relate to which property of water? Takes a great deal of energy to break H bonds for evaporation, heat is dispelled as water evaporates, high temperatures may damage enzymes.
high heat of vaporization
Your sweating and water boiling are examples of which property of water?
high heat of vaporization
Heat of _____ is the opposite of heat of vaporization.
fusion
The amount of heat energy that must withdraw to cause water to freeze or change from liquid to solid.
heat of fusion
Water’s _____ causes water molecules to align a particular way which results in air spaces, hence, solid water is less dense than liquid water. Also accounts for interesting formations like ice crystals and snow flakes.
polarity
Liquid water is more _____ than ice.
dense, because unlike other substances, water expands as it freezes, ice floats rather than sinks, it makes life possible in water, and ice acts as an insulator.
Water _____ into an equal number of hydrogen ions (H+) and hydroxide ions (OH-).
dissociates
The mathematical way to indicate the number of hydrogen ions in solution is called _____.
pH
The pH scale ranges from __________.
0 to 14; pH below 7 is acidic – more [H+] than [OH-]; pH above 7 is basic – more [OH-]than [H+]; pH of 7 is neutral – [H+] equal to [OH-].
Pure water has a pH of _____.
7
A _____ is a compound that accepts H+ in response to a pH change.
buffer
_____ are chemicals or combination of chemicals keeps pH within normal limits.
buffers
Buffers resist pH change by __________.
taking up excess H+ or OH-
Blood has a neutral pH. True or false?
False. pH of blood is about 7.4 – maintained by buffers – the main one is the bicarbonate ion. If the blood becomes too acidic, bicarbonate accepts (and absorbs) H+ to make carbonic acid.
