Chapter 2 Flashcards
Elements and compounds
Element- basic component of matter that cannot be reduced
Compound- composed of two or more elements. Have propertied unique from the two elements it is composed of.
What are the four essential elements for life?
Oxygen, hydrogen, Carbon, Nitrogen-96.3%
Atom and its subatomic parts
Smallest unit of matter that retain the propertied of an element.
- Neutrons
- Protons
- Electrons (no mass/daltons)
Isotopes
Radioactive isotopes?
Atoms of the same element that have a different number of neutrons.
Spontaneous decay of atomic nucleus, releasing particle and energy.
Used in medical imaging
What are the three types of chemical bonds? Which is strongest
?
- Ionic
- Covalent (strongest)
- Hydrogen
Which subatomic particle is the only one involved in chemical reactions?
Electrons, oceans differing amounts of energy depending on location to nucleus.
How to calculate mass #
neutrons+#protons
Covalent bond def
Molecule
Sharing of a pair of valence electrons by two atoms to become stable.
Two or more atoms held by a bond. The atoms can be the same element. In compounds they must be different in fixed ratio.
Electronegativity
The attraction of a given atom for the electrons of a covalent bond.
Non polar covalent bond
Type of covalent bond in which electrons are shared equally between two atoms of similar electronegativity.
Polar covalent bond
Covalent bond between atoms that differ in electronegativity. The shared electrons are pulled closer to the more electronegative atom making it slightly negative and the other atom slightly positive.
H20- hydrogen (+) pulled to oxygen (-)
What happens to potential energy as an electron is closer to the nucleus?
Potential energy decreases due to strong nuclear pull.
What type of bond does carbon form?
How many bonds can carbon make?
Non polar
4- more variability in molecules that make life.
Ions
A difference in electronegativity so great that one atom takes an electron from another resulting in the formation of ions.
Ionic compounds
Called salts, formed when two ions form an ionic bond.
Strength of ionic bond is dependent upon environment.
Hydrogen bonds
A type of weak chemical bond that is formed when the lightly positive hydrogen atom of a polar covalent bond in one molecule is attracted to the slightly negative atom.
-are weak individually but will maintain functional structure of biomolecules.
What are the van der walls interactions?
- electrons are in constant motion
- resulting in temporary formation of slightly positive and negative regions which attract each other.
- individually weak, but also stabilize three- dimensional shapes of biomolecules.
Molecules have specific ____ and ___?
Size and shape that they always make when formed.
Ex: tetrahedron shape is formed for methane (CH4)
When does equilibrium occur?
A chemical reaction in which the rate of the forward exactions equals the rate of the reverse.
What are the four properties of water that are essential for life?
- Cohesion
- Temperature moderation
- Expansion upon freezing
- Versatility as a solvent
Cohesion and adhesion
Co: Due to hydrogen bonding between water molecules
Ad: due to hydrogen bonding between after and other molecules.
What is specific heat? What is different about waters specific heat?
The amount off heat required for 1 g of the substance to increase its temp by 1 degree Celsius.
Water has a high specific heat that can stabilize temperatures
Cooler objects ______ thermal energy from warmer objects.
Absorb
Ice takes heat of drink which leads to it melting.
Heat of vaporization
Amount of heat required for 1 g of a substance to be converted from a liquid to a gaseous state.
Solutions
Solvent
Solute
Aqueous solution
Homogenous liquid mixture of 2 or more substances
Dissolving agent
Substance dissolved in a solution
Solvent is water
Hydration shell
Water molecules form hydrogen bonds with each solute molecule and surround it.
The sphere of water molecule around a dissolved ion
Evaporative cooling
The process in which the surface on an object becomes colder during evaporation, a result of the molecules with the greatest kinetic energy changing from liquid to gas.
Why does ice float?
Water is less dense as a solid. This is due to hydrogen bonding in ice. Each molecule is hydrogen bonded to four neighbours in a 3d crystal. Because the crystal is spacious ice has fewer molecules than the equal volume of water.
Transpiration
The exhalation of water through the stromatolites resulting in the absorption of water through the roots.
Cohesion holds water molecules together while adhesion helps water to cell walls to stop forces of gravity.
How is molecule mass calculated?
By adding up the masses of all atoms in molecule
How is molarity calculated
Moles divided by litres
Hydrophilic vs hydrophobic
Phyilic: A substance which has an affinity for water
-polar molecules and ions
Phobic: do not like water
-non polar and nonionic compounds (lack of charge)
Acid and Bases def
How to find ph
Acid- substance which increases the H+ concentration of a solution. (Strong acids dissociate completely)
Base- substance the decreases the H+ concentration of a solution.
Ph is a negative log scale. So 10-7 has a ph of 7
Buffers def
A substance that intimides changes in the H= concentration: stabilizes ph.
- comprised of a acid and a base
- donates or accepts H+ and OH- ions.
Hydroxide ion and hydronium ion
Hydroxide: a water molecule that has lost a Proton: OH-
Hydronium: A water molecule that has an extra Proton bound to it: H30.
