Chapter 2: The Chemical Foundation of Life

What is life composed of?

Matter

What are the two characteristics of matter?

Matter occupies space and has mass

Why are elements a unique form of matter?

They have specific chemical and physical properties

Can elements be broken down into smaller substances?

No

What are the four most common elements of living organisms (they make of 96% of the organism)?

Carbon, Oxygen, Hydrogen, Nitrogen

What is an atom?

The smallest unit of matter that retains all chemical properties of an element

What are the two regions of an atom?

Nucleus and the Outermost Region

What is the nucleus of an atom?

The center of the atom and contains protons and neutrons

What is the outermost region of an atom?

Region that holds electrons in orbit around the nucleus

What are protons, neutrons, and electrons referred to as?

Sub-atomic particles

How is atomic number calculated?

By the number of Protons

How is Atomic Mass calculated?

By adding the number of protons and neutrons

Can the number of neutrons vary in an element?

Yes

What is an element with a different number of neutrons called?

An Isotope

What is atomic mass expressed in?

Atomic Mass Units (AMU)

How do you calculate the number of neutrons of an element?

Subtract the atomic number from the atomic mass

What are radioisotopes?

Isotopes that emit neutrons, protons, and electrons

What takes advantage of radioisotopes?

Radiometric Dating

How do you know if an atom has a neutral charge?

The number of protons equal the number of electrons

What is the Bohr Model?

The early model with protons in nucleus and electrons in circular orbits at specific distance from nucleus

What are orbits?

Electron shells or energy levels

Where do electrons normally exist?

The lowest available energy shell (closest to the nucleus)

What is the outer shell called?

Valence Shell

What is the most stable configuration?

When the valence shell is filled

What are chemical reactions?

Changes in the distribution of electrons between atoms

What are reactants?

substances used at the beginning of the reaction

What are products?

substances formed at the end of the reaction

What is an irreversible reaction?

A reaction that proceeds in one direction until all the reactants are used up

What is a reversible reaction?

A reaction where reactants are converted to products but some product can be converted back to reactant

What is a chemical bond?

The attractive force that links atoms together to form molecules

What are covalent bonds?

A chemical bond where electrons are shared

What are oxygen atoms in an O2 molecule joined by?

A double bond

What are ionic bonds?

A chemical bond where atoms give up or gain electrons

In the formation of an ionic compound what loses electrons and what gains electrons?

Metals lose electrons and nonmetals gain electrons

What are Polar Bonds?

Covalent bonds in which there is an unequal sharing of the electrons

What does it mean when an atom has a higher electronegativity?

It will want the electrons more than the atom that it is sharing with

What are non-polar bonds?

Covalent Bonds in which there is equal sharing of electrons

What determines if a molecule is polar or nonpolar?

Bond type and molecular shape

What do ionic and covalent bonds need to break?

energy

What are hydrogen bonds?

interaction between the δ^+ of hydrogen and the δ^- of a more electronegative atom on another molecule – often occurs between water molecules

What are Van der Waals interactions?

Weak attractions or interactions between two or more molecules (in close proximity) due to changes in electron density

How much of the human body is made up of water?

60-70%

Why is water the most critical molecule for life?

It is a polar molecule and it forms hydrogen bonds

What are the chemical bonds between hydrogen and oxygen in water?

Polar Covalent Bonds

Oxygen has what type of charge?

Slightly negative charge

Hydrogen has what type of charge?

Slightly positive charge

Hydrogen of one water molecule forms what kind of bond with the oxygen of an adjacent water molecules?

A weak hydrogen bond

What are the three states of water?

Liquid water, gas, and solid water

How is liquid water made?

Hydrogen bonds are constantly made, broken and remade

How is gas made?

Water is heated the increased kinetic energy of water causes hydrogen bonds to break and water molecules escape into air as gas

How is solid water made?

Temperature is lowered and a crystalline structure is maintained

How does Hydrogen Bonding make ice less dense than liquid water?

The lattice structure of ice makes it less dense than the freely flowing molecules of liquid water, enabling it to float on water

What is heat capacity?

The amount of heat one gram of a substance must absorb in order to raise its temperature one degree Celsius

What is heat of vaporization?

The amount of energy required to change one gram of liquid substance to gas

What can dissolve in water?

Ions and Polar Molecules

What substance is being dissolved?

Solutes

What substance is doing the dissolving?

Solvent

What is Cohesion?

The attraction of like molecules

What does cohesion allow for?

The development of surface tension

What is surface tension?

The capacity of a substance to withstand being ruptured when placed under tension or stress

What is adhesion?

An attraction between water molecules and other molecules

What does the pH of a solution indicate?

Acidity or Alkalinity

What types of solutions are acidic?

Solutions with high H+ concentrations

What types of solutions are basic?

Solutions with high OH- concentration

What do buffers do?

Play a key role in maintaining the internal solutions of an organism at or near neutral pH

What atom is essential to life?

Carbon

What is Carbon a key component of?

Macromolecules

How many atoms a can carbon form a covalent bond with?

Up to four

The ability to bond with so many atoms allows Carbon to serve as what?

The “backbone” for the macromolecules

How many electrons are on the outer shell of carbon?

Four

How many covalent bonds does Carbon form in order to “fill” it’s outer shell?

Four

What is the octet rule?

The tendency of atoms to prefer to have eight electrons in the valence shell

What are Hydrocarbons?

Carbon + Hydrogen

What do covalent bonds between atoms in hydrocarbons store?

Energy

How is the energy in Hydrocarbon bonds released?

The molecules are burned

What are isomers?

Molecules that have the same chemical formula but differ in placement/arrangement of atoms or types of bonds between atoms

What are structural isomers?

Have a different covalent arrangement of atoms

What are geometric isomers?

Have a different arrangement of atoms around a double bond

What are enantiomers?

Molecules that share chemical formula and bonds but differ in 3D placement of atoms; mirror images

What are functional groups?

Groups of atoms within a molecule that confer consistent specific properties to these molecules

Do each of the four types of macromolecules have there own set of characteristics functional groups?

Yes

How do functional groups interact with other functional groups?

Interact via Hydrogen Bonds