Chapter Two Flashcards
Matter
Anything that has mass and occupies space
Element
Substance that cannot be broken into other substances by chemical means
Element is represented by
Chemical symbols
Essential elements
Elements that an organism needs to live and reproduce
Trace elements
Elements required by an organism in small amounts
Compound
Substance composed of two or more different elements
Compound represented by
Chemical formulas
Compounds have
A definite ratio
Electrons may have
different levels of energy within an atom
Energy
The ability to do work
Potential energy
stored energy that matter possesses due to structure or position
Electrons in energy levels closer to the nucleus have
lower energy than electrons that are farther from the nucleus
Valence Electrons
Electrons that are on the out most energy level of an atom; electrons that participate in bonding
Orbital
3-D space in which electrons are most likely to be found
Chemical bonds
Attraction between atoms
Ionic bond
Formed due to the attraction of oppositely charged ions following the transfer of electrons
Covalent Bond
Bond formed when adjacent atoms share one or more pairs of electrons
Molecule
Substance composed of two or more atoms joined through covalent bonds
Covalent bonds occur between
nonmetals
Electrons may not be shared
equally
Non polar covalent bonds
bonds in which electrons are shared equally
Non polar Covalent Bonds
bonds in which electrons are shared unequally
Electronegativity
determines whether polar or non polar bonds form
Electronegativity
Measure of the ability of an atom to attract electrons in a bond
Ionic Compounds
Compounds that form from the attraction of cation and anions
Cation
ion that forms after an atom loses one or more electrons
Possess positive charge
Metals tend to form
Cations
Anion
Ion that forms after an atom gains one or more electrons
Negative charges
Anions are formed
Between nonmetals
Properties of Ionic Compounds
hard and brittle
Higher melting and boiling points
Soluble in water
Conduct electrical current if melted or dissolved in water
Ionic Forces
Attractive forces that occur between positively charged cations and negatively-charged anions in ionic compounds
Dipole-Dipole
Attractive forces that occur between the partial positive charge of one molecule and the partial negative charge of an adjacent molecule
Dipole
Molecule that has a partial positive end and a partial negative end
Occurs between polar molecules
Hydrogen Bond
Attractive force that occurs when a hydrogen bound to a highly electronegative atom is attracted to lone electrons of an adjacent molecule
occurs when hydrogen is bound to N, O, or F
Special type of dipole dipole force
Van der Wals forces
Attractive forces that occur within non polar compounds; include London dispersion forces
London dispersion forces
Attraction due to a temporarily induced dipole
Occurs in non polar compounds
weakest of intermolecular forces
Molecular shapes are determined by the
position of the atoms’ orbitals
Molecular functions are influenced by
Number of bonds an atom has
The presence or absence of lone electrons around the atom
Molecular shape determines
how biological molecules recognize and respond to one another
Chemical reaction
The process of making and breaking of chemical bonds, resulting in changes in composition of matter
Reactants——> Products
Reversible reaction
Chemical reaction in which the reactants form products and products can reform into reactants
Reactants (double arrow) Products
Chemical Equilibrium
Condition in which the forward reaction and reverse reaction occur simultaneously and at equal rates
Relative concentrations of reactants and products are unchanging
