Chemistry of Life 1

Chemical bonds, properties of water, hydrogen bonds, pH

Understand parts of the atom

protons and neutrons in the nucleus; electrons outside the nucleus

Understand electrons are involved in all chemical bonds

since all atoms want to be stable, they have to fill their shells with electrons; they do this by forming chemical bonds to share or give/receive electrons which creates a bond

Ionic Bonds

transfer of electrons to another atom; ions are held together by their charge differences; metal gives away and nonmetal receives

Ion

atom or molecule with a pos or neg charge

Covalent Bonds (polar and non-polar)

bond where atoms share their electrons, usually between two nonmetals; in polar, they share it unequally because one has a stronger electronegativity; non-polar they share it equally

Understand how many electrons each orbital can hold

1st holds 2, the rest hold 8

Mass Number

total number of protons and neutrons in the nucleus

Atomic Number

number of protons in the nucleus

Isotopes

different forms of an element that have the same number of protons nut a different number of neutrons

Cation

positively charged ion

Anion

negatively charged ion

Hydrogen Bonds

attraction between a weakly positive hydrogen and weakly negative charged atom; weaker than ionic and covalent because it takes less energy to break these bonds (have less electrons); when bonds are formed, it releases energy

Van der Waals Forces

the force of attraction between two dipoles’ positive and negative side that accelerates and attracts the atoms together

Understand in a polar covalent bond such as water, which atom has a slight positive charge, which atom has a slight negative charge

oxygen has a negative charge and hydrogen has a positive charge

How many hydrogen bonds can one water molecule form

4

Cohesion

attraction of water to itself

Adhesion

attraction of water to another molecule

Hydrophobic

doesn’t like water

Hydrophilic

is attracted to water

Understand why oil and water don’t mix

oil is nonpolar so it doesn’t have a charge for the water molecules which are polar so the water cannot form hydrogen bonds to mix with it

Understand why Ice is less dense than water

the hydrogen bonds in solid form is more spread apart than in liquid form which makes it less dense

Specific Heat Capacity

the amount of energy it takes to raise the temperature; the higher the capacity, the harder it is to raise the temperature

Heat of Vaporization

amount of energy it takes to go from a liquid to a gas; water has a high one so that as you sweat, you’re releasing heat from your body; liquid turns to gas and releases heat

Understand the relationship of protons and hydroxide ions at a pH, below 7, at 7, and above 7.

at pH 7, protons and hydroxide ions are equal, below there’s more protons, above there’s more hydroxide ions

Understand how buffers work

a solution that can resist pH change upon the addition of an acidic or basic solution; the buffer will donate protons which increases acidity or absorb protons which increases the basic

When is an atom neutral?

they have the same number of electrons and protons

Explain if Methane (CH4) is polar or non-polar? Carbon has an electronegativity of 2.5, while Hydrogen has an electronegativity of 2.0.  If methane is polar, which atom has a slightly negative charge, and which one has a slightly positive charge?

polar because the difference in the electronegativities is 0.5 which means that they don’t have a similar attraction; hydrogen is slightly positive because it has a lower electronegativity 

What is the significance for aquatic organisms that ice is less dense than liquid water

it allows ice to float to the surface and for them to continue living

What types of molecules can dissolve in water?

polar

Why can’t lipids dissolve in water?

theyre nonpolar so the hydrogen can’t form bonds with it to dissolve it

Explain two different scenarios why water’s high specific heat capacity is important for living organisms in maintaining homeostasis

it maintains temperature inside the body and it makes it so the aquatic organisms don’t face massive temperature changes

Explain why water cohesion property is essential for survival of plants.

since it’s cohesive, the more hydrogen bonds form, the greater the force will be against gravity allowing the plant to get water from its roots

Explain why water’s high specific heat of vaporization is important for living organisms in maintain homeostasis.

it allows for the body to cool so that as you sweat and the water is turned into gas, it releases heat

what is the weak chemical bond that occurs when dipoles are attracted to one another due to opposite charge

dipole dipole bond