Ch. 2 Flashcards
When do Hydrogen bonds form and what does this cause?
Heat is released when hydrogen bonds form.
When do Hydrogen bonds break down and what does this cause?
Heat is absorbed when hydrogen bonds break.
Why is water a good solvent.
Polarity. Water has a negative and positive end.
Hydrophilic
Water loving
Hydrophobic
Water hating. Ex: Oils
Ph stands for what?
Potential Hydrogen
Elements
Unique forms of matter with specific chemical and physical properties that cannot be broken down into smaller substances by ordinary chemical reactions
The 4 elements common to all living organisms.
Oxygen (O)
Carbon (C)
Hydrogen (H)
Nitrogen (N)
What is amu?
Atomic Mass Unit or 1 “Dalton” 1.67 x 10^-24
Atomic Number
The number of protons in an element
Isotopes
Different forms of the same atom that vary only in the number of neutrons they possess
Mass Number
The amount of protons and Neutrons in an Element
Atomic Mass
The calculated mean of the mass number for its naturally occurring isotopes which often contains a fraction
Chemical Reactivity
The ability to combine and to chemically bond with eachother
Molecule
Two or more atoms chemically bonded together.
Chemical Reaction
Occurs when two or more atoms bond together to form molecules or when bonded atoms break apart
Reactants
Substance in the begging reactions
Adhesion
is an attraction between different substances, for example, between water and plant cell walls.
Cohesion
“Sticky.” Hydrogen Bonds hold water molecules together.
Surface Tension
is a measure of how hard it is to break the surface of a liquid. Related to Cohesion
Moderation of temperature by water
Water can absorb or release a large amount of heat with only a slight change in its own temperature.
Kinetic energy
The energy of motion
Heat
a measure of the total amount of kinetic energy due to molecular motion.
Temperature
measures the intensity of heat due to the average kinetic energy of molecules
Calorie (cal)
the amout of heat required to raise the temperature of 1 g of water by 1 degree C
Kilocalories (kcal)
the “calories” on food packages. 1 Kcal = 1,000 cal
Specific heat
the amount of heat that must be absorbed or lost for 1 g of that substance to change its temperature by 1 degree C
Specific heat of water
1cal/g/ degree C
Why does water resist changing its own temperature?
Water has high specific heat
Evaporation
transformation of a substance from liquid to gas
Heat of vaporization
the heat a liquid must absorb for 1 g to be converted to gas
Evaporative cooling
As a liquid evaporate, its remaining surface cools. This is what helps stabilize temperatures in organisms and bodies of water
