Ch.2 The Chemical Context of Life Flashcards
Atom
The smallest unit of matter that still retains the properties of an element
Subatomic particles
Tiny bits of matter composed of even smaller parts
Neutrons
Electrically neutral
Protons
Electrically positive charged
Electrons
Electrically negative charged
Atom nucleus
Where protons and neutrons are tightly packed in a dense core
Dalton
Measurement unit used to measure atoms (atomic mass unit)
Atomic number
Number of protons and electrons, written to left of the symbol of an element
Mass number
The sum of protons and neurons in the nucleus of an atom, written to the left of an element’a symbol
Atomic mass
Approx. the total mass of an atom
Isotopes
Different atomic forms of the same element, have more neutrons than other atoms of the same element
Radioactive isotope
One in which the nucleus decays spontaneously giving off particles and energy
Energy
The capacity to cause change, doing work
Potential energy
The energy that matter possess because of it’s location or structure
Element
A substance that cannot be broken down to other substances by chemical reactions
Compound
A substance consisting of two or more different elements combined in a fixed ratio
Emergent properties
Matter not possessed by it’s constituents
Essential elements
What organism need to live a healthy life and reproduce
Trace elements
Required elements by an organism in only minute quantities
Goiter
Iodine deficiency
Electron shells
Where electrons are located, the energy level
Valence electrons
The outermost electrons in a electron shell
Valence shell
The outermost electron shell
Inert
Chemically unreactive
Covalent bonds
Chemical bond that shares a pair Of valence electrons by two atoms
Single bond
A paired of shared electrons
Double bond
Sharing two pairs of valence electrons
Valence
Bonding capacity, equals the number of electrons required to complete the atoms outermost valence shell
Electronegativity
The attraction of a particular atom for the electrons of a covalent bond
Nonpolar covalent bond
Two atoms of the same element equally sharing electrons because the two atoms have same electronegativity
Polar covalent bonds
An atom is bonded to a more electronegative atom, the electrons are not shared equally
Ion
A charged atom ( molecule )
Cation
Positively charged ion
Anion
Negatively charged ion
Ionic bond
Attraction between cations and anions
Ionic compound (salts)
Compounds formed by ionic bonds
Hydrogen bond
Noncovalent attraction between a hydrogen and electronegative atom
Van der Waals interactions
Individually weak atoms occurred when atoms and molecules are very close together
Chemical reactions
The making and breaking of chemicals bonds, leading to changes in the composition of matter
Chemical equilibrium
The point at which the reactions offset one another exactly
Polar molecule
Unequal sharing of electrons and water’s V-like shape, Overall charge is unevenly distributed
Cohesion
The linking together of like molecules, often by hydrogen bonds
Adhesion
The clinging of one substance to another
Surface tension
A measure of how difficult it is to stretch or break the surface of a liquid
Kinetic energy
The energy of motion
Thermal energy (total thermal energy)
The random movement of atoms or molecules
Total thermal energy of a body of matter - depends on part of the matter’s volume
Temperature
Represents the average kinetic energy I the molecules, regardless of volume
Heat
Thermal energy in transfer from one body of matter to another
Calorie
The amount of her it takes to raise the temperature of 1 g of water by 1 degrees Celsius
Kilocalorie
The quantity of heat required to raise the temperature of 1 kilogram of water by 1 degrees Celsuis
Specific heat
The amount of heat that must be absorbed or lost for 1 g of that substance to change its temperature by 1 degrees Celsuis
Joule
Energy unit 1 joule = 0.239 cal.
1 cal. = 4.184 j
Heat of vaporization
The quantity of her a liquid must absorb for 1 g of it to be converted from liquid to the gaseous state
Evaporative cooling
Occurs because the “hottest” molecules, those with the greatest kinetic energy, are the ones most likely to leave as gas
Solution
A liquid that is a completely homogenous mixture of two or more substances
Solvent
The dissolving agent of the solution
Solute
The substance that is dissolved
Aqueous solution
One In which water is the solvent
Hydration shell
The sphere of water molecules around each dissolved ion
Hydrophilic
Any substance that has an affinity for water
Hydrophobic
Substance that are nonionic and nonpolar ( otherwise cannot form hydrogen bonds) repel water
Molecular mass
The sum of the masses of all the atoms in a molecule
Mole
An exact number of objects 6.02x10^23 ( Avogadro’s number)
Molarity
The number of moles of solute per liter of solution
Hydrogen ion
A single proton with a charge of 1+
Hydroxide ion
A single proton that has a charge of 1-
Hydronium ion
A water molecule that has an extra proton bound to it ( H3O+)
Acid
A substance that increase the hydrogen ion concentration of a solution
Base
A substance that reduces the hydrogen ion concentration of a solution
Ph of a solution
Negative logarithm (base 10) of the hydrogen ion concentration ( ph = - log[H+] )
Buffer
A substance that minimizes changes in the concentrations of H+ and OH - In a solution ( accepting hydrogen ions from the solution when they are in excess and donating hydrogen ions to the solution when the have been deplete)
The reactivity of an atom arises from…
The existence of unpaired electrons in the valence shell
The mole of table sugar and a mole of vitamin C are equal in their mass of
Number of molecules
