Atoms, Electrons & Chemical Bonding Flashcards
Atomic Number
Number of protons in the nucleus
Mass number
Sum of protons + neutrons in the nucleus
Isotopes
Same number of protons, different number of neutrons
How was wave particle duality discovered?
Schrodinger combined 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
What does wave equation give?
A series of solutions called wave functions
Quantum numbers
A whole number which specifies the shell and is related to the energy of the orbital
Angular Momentum Quantum Number
Usually designed by a letter (s,p,d,f) and describes the shape of the orbital
Nodal surface
A region where the probability of finding an electron is zero
What do s orbitals increase with?
The number of nodal surfaces
Pauli Exclusion Principle
No 2 electrons in the same atom can have the same set of 4 quantum numbers
Shape of p orbitals
Dumbells
When do p orbitals become possible?
When the quantum number, n = 2 and higher
What is an ionic bond formed between?
Metals and nonmetals with very different electronegativity
Properties of Ionic bonds
Conductors and have high melting points
Electronegativity
The measure of the ability of an atom to attract a pair of electrons
How does electronegativity differ across the periodic table?
Increases across the period
Decreases down the group
Most electronegative element
Fluorine
Least electronegative element
Francium
What are covalent bonds formed between?
nonmetallic elements of similar electronegativity
Bonds in all polyatomic ions and diatomics
Covalent bonds
What draws atoms closer together in covalent bonds?
The mixing of energy sublevels
Bond energy
The energy required to break a covalent bond, which is the same as the amount of energy released when the bond is formed
Non-polar covalent bonds
When electrons are shared equally
Polar Covalent bond
When electrons are shared but unequally
Properties of Metals
Good conductors, lustrous, high melting points
Octet rule
The tendency for atoms to seek 8 electrons in their outer shell
Electron Dot Formulas
The number of dots around each atom is equal to the number of valence electrons the atom has
When does a sigma bond occur?
When the bonding orbitals point along the axis connecting the two bonding nuclei
When does a pi bond occur?
When the bonding orbitals are parallel to each other and perpendicular to the axis connecting the two bonding nuclei
Why are sigma bonds stronger than pi bonds?
The interaction between parallel orbitals is not as strong between orbitals that point at each other
Resonance
The two shared electron pairs consitute a double bond
Resonance
The two shared electron pairs consitute a double bond
