Water and Chemistry 101
elements
-made up of one kind of atom -make up the periodic table
the pH scale
0 to 14 0-6.9- acid 7.1-14 - base 7 - neutral
how many atoms and molecules does 2H2+02->2h2o
2 atoms 3 molecules
what percent of organisms are made up of chnops
97%
How does water help cells keep an even temperature despite temperature changes in the environment
Because of hydrogen bonds, water must gain or lose a relatively large amount of energy for its temperature to change. it tends to resist temperature changes
What six elements are most important in organisms
Carbon, hydrogen, oxygen, nitrogen, phosphorus, and sulfur
How are chemical reactions important in cells
Chemical reactions form new molecules needed for growth and repair and make energy available for cellular activity
What is the relationship between atoms and elements
Elements are made up of particles called atoms
Neutral
H+ = OH-
Distinguish among the various types of chemical bonds
Ionic bonds involve a transfer of electrons. Covalent bonds involve sharing of electrons. Polar covalent bonds is where the electrons are shared unequally. Hydrogen bonds form between a slightly positive hydrogen of one polar molecule and a slightly negative atom of another.
Why is pH important to living organisms
It helps to regulate a cell's chemical reactions
Describe the law of conservation of matter
It states that matter is neither created nor destroyed in chemical reactions
Why is water a good solvent
It's polar nature allows it to dissolve other polar substances as well as ionic compounds
What are the particles of an atom and how do they interact
Protons and neutrons form the atomic nucleus. electrons are present as a cloud around the nucleus. the number of protons and electrons are equal, so an atom has no charge
How does the polarity of water assist the movement of molecules
The polarity of water molecules allows them to dissolve many substances, facilitating their movement within and between cells. Also, the ability of water molecules to form hydrogen bonds helps stabilize large molecules such as proteins and nucleic acids.
A fire can be started by rubbing 2 sticks together until the wood ignites. What is this an example of
activation energy
What property of water allows it to stick to a dry surfaces
adhesion
How does capillary action occur
adhesion- water is attracted to molecules of another substance cohesion- water molecules attracted to each other defined as water moving up the vessels of plants
hydrogen bond
an attraction between a positive hydrogen atom in a molecule and a region of negative charges in another
cohesion
an attractive force between same substances
adhesion
an attractive force between unlike substances
If an atom or molecule gains or loses an electron, what does it become
an ion
What kinds of substances besides water can be involved in hydrogen bonding
any molecule that has a region of negative charge or a hydrogen with a slight positive charge can be involved in hydrogen bonding
isotopes
atoms of the same element that differ in the number of neutrons radioisotopes- unstable nuclei
hydrogen bonds
between a hydrogen (H+) atom and a region of (-) charge in another atom
ion
charged atom that is positive or negative
When a glass is filled to the brim with water, the water appears to bulge from the side of the glass due to what
cohesion
Explain why water forms large, round drops as they fall from a faucet with a slow leak
cohesion forces causes the water molecules in each drop to move as close as possible to one another making the drop round
Chemical reactions occur in living cells, what is this reaction not important to
creation of new elements
polar covalent
electrons are not shared equally
nonpolar covalent
electrons are shared equally
what does chemical bonding form
forms molecules or compounds between elements
When liquid water is heated, most of the energy that the water initially absorbs is used to break down what
hydrogen bonds between water molecules
Describe the surface tension of water
it is greater than other substances since hydrogen bonds resist breaking
Water is often called a universal solvent because it dissolves most substances that are important to living things. What does this suggest about the nature of those substances
it suggests that that the substances are most often polar molecules or ionic compounds
freezing
liquid water becomes ice, less dense than water, at 4 degrees Celsius hydrogen bonds expand
acids
more H+ than OH-
bases
more OH- than H+
Which type of bonding occurs when electrons are shared equally
nonpolar covalent
When water is boiled, what happens to its chemical composition
nothing
atomic number
number of protons
atomic mass
number of protons and neutrons
When does hydrogen bonding occur in water
occurs between separate water molecules
polar compound
one with an uneven distribution of positive and negative charges
What element is most abundant in the human body
oxygen
What type of bond in water
polar covalent bond
the subatomic particles making up an atom are
protons, neutrons, and electrons
Describe heat of vaporization of water
quantity of heat required to convert liquid water to gas example is sweating- evaporative cooling to prevent sweating
chemical equations
reaction yields products
Describe the high specific heat of water
resistant to changes in temperature, high boiling point, moderates temperature in organisms
When sodium chloride is dissolved in water, what are the sodium ions attracted to
sodium ions are attracted to oxygen atoms of water molecules
A dissolving substance
solute
activation energy
the energy needed to start a reaction
what do reactions involve
the making and breaking of chemical bonds
In a water molecule, which atom has a slightly negative charge and which one has a slightly positive charge
the oxygen has a slightly negative charge and the hydrogen atoms have a slightly positive charge
What does C6H12O6 not tell
the position of atoms
What is water known as
the universal solvent
ionic bonding
transfer of electrons
ionization of water
water dissociates into ions- H+ ions, OH- ions (hydr
