matter and energy
what is kinetic energy?
energy that comes from motion
what are electrons?
negatively charged particles found in the electron cloud
what are valence electrons
elements in the same column share similar properties because they have the same number of these
what is covalent bonding?
bonding formed by sharing electrons between nonmetals
why metals conduct heat well
because free (delocalized) electrons transfer energy efficiently
what is the first law of thermodynamics?
the law stating energy cannot be created or destroyed, only transformed
what is atomic number
the number that defines the identity of an element
what is atomic radius?
this trend decreases across a period due to increasing nuclear charge
what is metallic bonding?
bonding that explains why metals are conductive and malleable
why atomic radius increases down a group
because additional energy levels increase distance from the nucleus
what is from hot to cold?
Heat always flows in this direction until thermal equilibrium is reached
what are isotopes
atoms of the same element with different numbers of neutrons
what is ionization energy
the energy required to remove an electron from an atom
what are intermolecular forces
attractive forces between molecules that include hydrogen bonding and dipole-dipole forces
why ionic compounds conduct electricity when molten but not solid
because ions are free to move when molten
what is temperature
this measures average kinetic energy of particles, not total energy
what is the modern atomic theory (quantum mechanical model)
the model that uses probability regions instead of fixed electron paths
what is electronegativity
the tendency of an atom to attract electrons in a bond
what is a polar covalent bond
this type of bond has an electronegativity difference between 0.4 and 2.0
why CO2 is nonpolar even though it has polar bonds
because the molecule is symmetrical, so dipoles cancel
what is entrophy
a measure of disorder that increases during spontaneous processes
what is hesienburg's uncertainty principle
this principle states you cannot know both an electron's exact position and momentum
what is the shielding effect
inner electrons blocking the nucleus from outer electrons
what is a bent and polar?
the geometry and polarity of H2O
why stronger intermolecular forces lead to higher boiling points
because more energy is required to separate the molecules