Ch. 2 The Nature Of Molecules And The Properties Of Water Flashcards
_______ have a nucleus made of _______ and ______ which is surrounded by orbiting ______. The numbers of these particles determine the character of an element.
Atoms; protons; neutrons; electrons
What’s the charge of each sub-atomic particle? Protons? Neutrons? Electrons?
Positive, neutral (no charge), negative
Any substance in the universe that has mass and occupies space is defined as ______
Matter
All matter is composed of extremely small particles called ________
Atoms
Different atoms are defined by the # of protons, a quantity called the ________ ________
Atomic number
An _______ is any substance that cannot be broken down to any other other substance by ordinary chemical means
Element
The ________ of an atom is equal to the sum of the masses of its protons and neutrons.
Atomic mass
The mass of atoms and subatomic particles is measured in units called _________
Daltons
Electrons are located in regions called _________ along atom _________
Orbitals; shells
An atom with an unequal amount of protons and electrons is known as a(n) _______
Ion
Atoms with more protons than electrons, being positively charged are called ________
Cations
Atoms with more electrons than protons, being negatively charged are called ______
Anions
Atoms of a single element with different numbers of neutrons are called _______
Isotopes
Decay time is expressed as ________
Half-life
No orbital can contain more than _______ electrons
Two
The loss of an electron is called ______, the gain of an electron is called _______
Oxidation; reduction
When oxidation + reduction occur at the same time
Redox reactions
Electrons on outermost energy level/shell
Valence electrons
Electrons possessing all eight electrons in their outer most energy level are _______, these elements are known as ________
Nonreactive; noble gasses
A group of atoms held together by energy is called a ______
Molecule
Molecules contains atoms of more than one element are called _______
Compounds
Atoms within molecules are joined by _______
Chemical bonds
_______ bonds occur when opposite charges attract each other (Na- Cl+)
Ionic
________ bonds occur when atoms share one or more pair of valence electrons (sharing) H2O
Covalent
Atoms differ in their affinity for electrons, a property called ________
Electronegativity
The strength of covalent bonds is dependent on the number of shared _______
Electrons
Bonds between identical atoms, with the affinity for electrons being the same are termed ________
Non polar
Atoms that differ greatly in electronegativity, where electrons can not be shared as easily/equally are termed _______
Polar
When drawing polar molecules, partial charges are symbolized by the lowercase Greek letter _________
Delta (S)
The formation and breaking of chemical bonds is termed a _______
Chemical reaction
Original molecules________, result from reaction _________
Reactants; products
What 3 factors increase the rate of a reaction?
Heat/Temperature; concentration of reactants/products (more reactants available=more frequent collisions); catalysts i.e. enzymes
Many reactions in nature are _______, meaning _________ may also be __________
Reversible; products; reactants
How is a covalent bond different from an ionic bond?
An ionic bond results when there is a complete ‘ ‘ transfer of electrons between atoms, resulting in positive and negative ions that are attracted to each other. Covalent bonds are the result of two atoms sharing electrons. Polar covalent bonds involve unequal sharing of electrons, producing regions of partial charge. (Draw examples)
_________ bonds form between the partially negative O atoms and the partially positive H atoms of two water molecules
Hydrogen Bonds
Water likes substances with which it can form hydrogen bonds. _______ is responsible for ___________. (The polarity of water causes it to be attracted to other polar molecules as well)
Adhesion; Capillary action
The polarity of WATER allows WATER molecules to be attracted to one another, this property is known as _________. _______ is responsible for __________.
Cohesion; surface tension
Hydrogen bonds absorb heat when they break and release heat when they form, minimizing temp changes.
High specific heat
Water stabilizes the temp of organisms and the environment
High specific heat
Many hydrogen bonds must be broken for water to evaporate
High heat of vaporization
Evaporation of water cools body surfaces
High heat of vaporization
Water molecules in an ice crystal are spaced relatively far apart because of hydrogen bonding
Lower density of ice
Due to the ___________, lakes do not freeze solid, allows fish & other life in lakes to survive the winter
Lower density of ice
Polar water molecules are attracted to ions and polar compounds, makings these compounds _________
Soluble; solubility
Many kinds of molecules may move freely in cells, permitting a diverse array of chemical reactions
Solubility
________ molecules shrink from contact with water. Water molecules act to exclude them.
Hydrophobic; water-hating
Polar molecules, which readily form hydrogen bonds with water are considered ________
Hydrophilic; water-loving
A _______ is defined as the weight of a substance in grams that corresponds to the atomic masses of all the atoms in a molecule of that substance
Mole
The concentration of hydrogen + hydroxide ions in a solution is described using _______
Acidity & basicity
The pH scale is________, a difference of 1 on the scale represents a 10-fold change in ___.
Logarithmic; H+
Any substance that dissociates in water to increase the ____ & ______ the pH is called an _______
H+; lower; acid
Any substance that combines with ____ when dissolved in water, lowering the ____ is called a ______
H+; H+; base
The _______ an ______ is, the more _______ ions it produces and the ________ its pH
Stronger; acid; hydrogen; lower
A ______ is a substance that resists change in pH.
Buffer
_______ act by _________ hydrogen ions when a base is added and __________ hydrogen ions when acid is added, with the overall effect of keeping _______ relatively constant.
Buffers; releasing; absorbing; H+
__________ bonds involve unequal sharing of electrons, producing regions of partial charge.
Polar covalent
Any substance that has mass + occupies space
Matter
All matter is composed of small particles called ______
Atoms
At the center ______, made up of _______ + _______
Nucleus;protons;neutrons
of protons, otherwise known as ________;
Atomic Number
Substance that cannot be broken down to other substance by normal means
Element
Proton (); Electron (); Electrically neutral if ______
Positive;Negative;Equal
Amount of a substance
Mass
Force gravity exerts on a substance
Weight
Sum of proton + neutron masses
Atomic Mass
Mass of atoms & subatomic particles expressed in ______
Daltons
Electrons are maintained in their _______ by their attraction to ______ charged nucleus
Orbitals;positively
Electrons not equally protons results in formation of
Ions
Protons>electrons
Cations (NA+)
Protons
Anions(Cl-)
Single element with dif # of neutrons results in
Isotopes
Unstable, ________ decay -> radioactive ________; decay expressed as ______
Radioactive;isotopes;half-life
No orbital can contain more than ______ electrons
Two
Atoms contain ________ _______ levels
Discrete;energy
Loss of electron = _______
Oxidation
