atoms,electrons and chemical bonding Flashcards
atomic number and mass number
atomic number (Z)= number of
protons in nucleus
mass n umber (A) =sum of the number of protons + neutrons in nucleus
A
X
Z
protons, neutrons, electrons
protons- positive 1.6726 x 10^-27
neutrons- neutral 1.6750 x 10^-27
electrons- negative 9.1096 x 10^-31
wave particle duality
schrodinger comined the idea that an electron has wave properties with classical equations of wave motion to give a wave equation for the energy of an electron in an atom
wave equations gived a series of solutions called wave functions
s orbital
spherically symmetric
increases with the number of nodal surfaces (is a region where the probability of finding an electron is zero) it has
the pauli exclusion principle
no two electrons in the same atom can have the same set of four quantum numbers.
two electrons can occupy the same orbital only when they have opposite spins
2 electrons per orbital
p orbitals
they are dumbell shaped
order of progression of the orbitals
1s
2s
2p
3s
3p
4s
3d
4p
4d
ionic bond
bond formed between two ions by the transfer of electrons
resulting when metals react with nonmetals
metals lose electrons to match the number of valence electrons of noble gas
electronegativity
the measure of the ability of an atom to attract electrons to itself
increase across period (left to right)
decrease down group (top to bottom)
fluorine is the most electronegative element
francium is the least electronegative element
covalent bond
between nonmetallic elements of similar electronegativity
formed by sharing electron pairs
stable non-ionizing particles, they are not conductors at any state
bond length
the valence shells of the two atoms overlap with each other
the distance between the two atoms is smaller than the sum of their atomic radii and is the bond length.
the energy required to break a covalent bond is referred to as the bond energy. same amount of energy to form and break the molecule
non polar covalent bond and non polar
when the electrons are shared equally and polar are when the electrons are shared but unequally
metallic bond
bonds found in metals; holds metal atoms together very strongly
formed between atoms of metallic elements
electron cloud around atoms
good conductors with very high melting points
octet rule
the tendency for atoms to seek 8 electrons in their outer shells
molecular orbital theory
sigma bond is a single bond
pi bond is in a double bond with two sigmas bonds
resonance
the two shared electrons pairs constitute a double bond
the double bond can be placed between the sulfur and any of the three oxygen atoms
