ppt 2 Flashcards
Most of the mass is in the ______
nucleus
containing protons and neutrons
Surrounded by an electron cloud containing electrons in a large volume of space
nucleus
protons + neutrons
Most of the volume is in the _______
electron cloud
variation of an element that possesses the same atomic number but a different mass number
any element will always have the same number of protons and electrons
They will differ in the number of neutrons held by their respective nuclei.
isotopes
the exact location of the electron cannot be known; only the electron density can be known
Quantum Mechanical Model
the probability that the electron will be in a certain region of space (orbital) at a given instant
Electron density
Electrons do not circle around the nucleus in fixed orbits but rather in _______
Each _____ has a characteristic shape and size (energy)
orbitals
used to describe orbitals
QUANTUM NUMBERS
Principal
- n
- Size (energy level, shell)
- positive integers (1,2,3,…)
Azimuthal/ Angular Momentum
- l
- Shape (subshell)
- 0 to (n-1) / s, p, d, f
Magnetic
- ml
- Orientation (orbital)
- (-l to +l)
Electron Spin
- ms
- Direction
- +1/2,-1/2
each box represents ________
one orbital
each cluster of boxes represents _________
one subshell
each row represents ________
one shell
describes the orbitals occupied by the atom’s electrons when they are all in the available orbitals with the lowest energy
Ground-state electron configuration
states that an electron occupies orbitals in order from lowest energy to highest (increasing order)
Aufbau Principle
Every orbital in a sublevel is singly occupied before any orbital is doubly occupied.
All of the electrons in singly occupied orbitals have the same spin (to maximize total spin).
Hund’s Rule
no two electrons can have the same four electronic quantum numbers.
As an orbital can contain a maximum of only two electrons, the two electrons must have opposing spins.
This means if one electron is assigned as a spin up (+1/2) electron, the other electron must be spin-down (-1/2) electron.
Pauli’ Exclusion Principle
states that we cannot know both the position and speed of a particle, such as a photon or electron, with perfect accuracy;
the more we nail down the particle’s position, the less we know about its speed and vice versa
Heisenberg’s Uncertainty Principle
electrons below the outermost shell
Core electrons
electrons in the outermost shell
Valence electrons
an attractive force between two ions or between two atoms
CHEMICAL BOND
Why do chemical bonds form?
Because the compound that results is more stable and lower in energy than the separate atoms
How do chemical bonds form?
Octet rule
atom is most stable if its outer shell is either filled or contains eight electrons, and it has no electrons of higher energy
OCTET RULE
An atom will give up, accept, or share electrons in order to achieve a filled outer shell containing eight electrons EXCEPT _______ and ________
hydrogen and helium
Chemistry of main-group elements is governed by their tendency to take on the electron configuration of the nearest
noble gas
attractive forces between opposite charges
Electrostatic attraction
- bond formed as a result of the electrostatic attraction between ions of opposite charge
- bond formed from the transfer of electrons
- usually formed from the reaction of metals with nonmetals
Ionic bond
compounds formed by ionic bonds
Ionic compound
bond formed as a result of sharing electrons between two nuclei
COVALENT BOND
compounds formed by covalent bonds
Molecular compounds
measure of the ability of an atom to pull the bonding electrons toward itself
ELECTRONEGATIVITY
a covalent bond between atoms with the same electronegativity
nonpolar covalent bond
covalent bond between atoms with different electronegativities
polar covalent bond
bond where no electrons are shared; opposite charges attract each other
ionic bond
bond where electrons are shared equally
nonpolar covalent bond
Polar molecules have _______
dipoles
a pair of equal and oppositely charged poles separated by a distance
Dipole