Octet rule Flashcards
Octet rule
- what does it form
- where does it occur
- what does it provide
- the electron pair…
- covalent bonds
- between 2 non metals
- each provides an electron to the sharing relationship
- spends time with both nuclei so each feels like they have an octet
In the simplest covalent molecule, H2, the H atoms
- increase attraction as they move closer
- share electrons to form a covalent bond
- the new compound is called a molecule
The need for an octet is so great for what?
H, O and S and group 17 elements that they do not exist as free atoms
How is the number of covalent bonds determined
from the number of electrons needed to complete an octet
in a methane (CH4) molecule…
- the central C atom shares 4 electrons to attain an octet
- each H atom shares 1 electron with the carbon atom to become stable like He
Average bond lengths
- C-H
- N-H
- O-H
- 109 pm
- 101 pm
- 96 pm
What happens when sharing one pair does not make an octet?
- in a single bond
- in a double bond
- in a triple bond
- one pair of electrons is shared
- 2 pairs of electrons are shared
- 3 pairs of electrons are shared
In an oxygen molecule…
- each O atom shares 2 electrons
- each O atom attains an octet
- the sharing of 2 sets of electrons is a multiple bond called a double bond
In a nitrogen molecule…
- each N atom shares 3 electrons
- each N atoms attains an octet
- the sharing of 3 sets of electrons is a multiple bond called a triple bond
Resonance structure
- 2 or more electron dot formulas for the same arrangement of atoms
- related by a double - headed arrow
- written by changing the location of a double bond between the central atom and a different attached atom
When are prefixes used in nonmenclature for covalent compounds?
- in the names of covalent compounds
- because 2 nonmetals can form two or more different compounds
Valence shell electron pair repulsion theory
- what is it the result of
- how are they arranged
- have the least amount of what
- have what shapes
- the result of bonded groups and lone pairs of electrons around the central carbon atom
- arranged as far apart from eachother as possible
- have the least amount of repulsion of the negatively charged electrons
- have a geometry around the central atom that determines molecular shape
Trigonal planar
- example
- how many electron groups are bonded
- what happens to repulsion
- BF3
- 3 electron groups are bonded to the central atom B
- repulsion is minimized with 3 electron groups at angles of 120
Bent
- example
- how many electron groups are bonded
- what happens to repulsion
- SO2
- 2 electron groups bonded to O atoms and one lone pair
- repulsion is minimized with the electron groups at angles of 120
Tetrahedral
- example
- how many electron groups
- what happens to repulsion
- CH4
- 4 electron groups around C
- repulsion is minimized by placing 4 electron groups at angles of 109
Trigonal pyramidal
- example
- how many electron groups are bonded
- how many electron groups minimize repulsion
- degrees
- what type of arrangement
- H2O
- 2 electron groups are bonded to H atoms and 2 are lone pairs
- 4 electron groups
- 109
- tetrahedral
Polar covalent bonds
- definition
- occurs between
- electronegativity difference
- unequal sharing of electrons
- nonmetal atoms
- moderate (0.5-1.7)
electronegativity value
- what does it indicate
- how does it increase
- how does it decrease
- what is it high for
- what is it low for
- attraction of an atom for shared electrons
- left to right
- down a group
- nonmetals with flourine as the highest
- metals
nonpolar covalent bond
- what does it occur between
- equality
- electronegativity difference
- nonmetals
- has an equal or almost equal sharing of electrons
- almost none (0.0-0.4)
ionic interaction
- occurs between
- result of
- electronegativity difference
- metal and nonmetal ions
- electron transfer
- large (>1.8)
nonpolar molecule
- contains
- arrangement
- nonpolar bonds
- symmetrical arrangement of polar bonds
dipole-dipole attractions
exert attractive forces
dispersion forces
- definition
- caused by
- attractions between nonpolar molecules
- temporary dipoles that develop when electrons are non distributed equally
what are the strongest type of dipole-dipole attractions
hydrogen bonds because they require more energy to break
what are the weakest interactions
dispersion forces because they require very little energy needed to change state
nuclear chemistry
the only subdiscipline of chemistry where the composition of the nucleus changes
radioactive isotope
- type of nucleus
- omits
- how many isotopes
- unstable
- radiation to become more stable
- can be 1 or more of the isotopes of an element
nuclear radiation
radiation admitted by an unstable atom
takes the form of alpha particles, neutrons, beta particles, positrons, or gamma rays
alpha particle
- protons and neutrons
- definition
2 protons and 2 neutrons
-heavy and do not travel far
beta particle
- energy
- mass
- travel
high energy electron
- less mass
- farther and through more things
positron
positive electron
gamma ray
- energy
- travel
high energy released from a nucleus
-through solid objects
radiation protection
- alpha particles
- beta particles
- gamma rays
- paper and clothing
- lab coat or gloves
- lead shield
- thick concrete wall
nuclear equation
- represents
- sums
- atomic number changes?
- what will help you know what the new element will be
- nuclear reaction
- mass and atomic numbers must be equal on both sides
- elements symbol changes to match
- type of radiation
geiger counter
- what does it measure
- detects
- what does it use
- units
- radiation
- beta/gamma
- ions produced by radiation to create an electrical current
- curie
curie
measues activity as the number of atoms that decay in one second
radiation absorbed dose
measures the radiation absorbed by one gram of body tissue
radiation equivalent in humans
- equation
- definition
- radxfactor
- measures the biological damage caused by different types of radiation
nuclear fission
bombardment of a heavy nuclei
