Lewis Dot Structure, EDG, MG, Electronegativity and Bond Polarity Flashcards
are diagrams that represent the valence electrons
of atoms within a molecule.
This help visualizes the valence electron/s of atoms and molecules, whether they exist as lone pairs or within bonds.
lewis/electron dot structure
rule no. 1 in lewis dot structure
Finding the number of electrons available for distribution is done by adding the valence electrons of all the atoms in the molecule or polyatomic ion. For positively charged polyatomic ions, the numerical charge is deducted from the total valence electrons. For negatively charged ions, the numerical charge is added.
rule no. 2 in lewis dot structure
In arranging the atoms, the least electronegative atom is assigned as the central atom. Hydrogen can form only one covalent bond so it is automatically designated as the terminal atom. Halogens are also usually assigned as terminal
atoms; but in cases, they serve as central atoms. When atoms are arranged, they are each connected by a single covalent bond first
- Each bond accounts for two electrons. To find the remaining electrons available for distribution, subtract those used for bonding from the total
electrons computed in rule no. 1.
rule no. 3 in lewis dot structure
The remaining electrons from rule no.2 are distributed to the atoms such that there are two electrons for hydrogen (satisfying the duplet rule) and eight electrons for the other atoms (satisfying
the octet rule).
rule no. 4 in lewis dot structure
If there are not enough electrons for the atoms to have 8 electrons each, the single bonds are changed to double or triple bonds by shifting nonbonding pairs of electrons as needed
rule no. 5 in lewis dot structure
If there are more than one Lewis structure that result in rule no. 4, the one that is symmetrical is usually chosen. The concept of formal charge also helps determine the acceptable Lewis structure.
rule no. 6 in lewis dot structure
The structure of a polyatomic ion is enclosed in brackets and the charge is placed at the upper right corner of the bracket
is the charge assigned to an atom in a molecule, assuming that electrons in all chemical bonds are shared equally between atoms, regardless of relative electronegativity. When determining
the best Lewis structure (or predominant resonance structure) for a molecule, the structure is chosen such that the this on each of the atoms is as close to zero as possible.
formal charge
formula of formal charge
(no. of valence e-) minus (no. of unshared e-)
minus 1/2 (no. of shared e-)
It refers to the tendency of atoms to prefer to
have eight electrons in the valence shell except
for hydrogen because it is stable with two
electrons (duplet rule).
When atoms have fewer than eight electrons, they
tend to react and form more stable compounds.
octet rule
which sublevels are involved in the octet rule, making it useful for the representative
elements (Group A elements)
s and p sublevels
bonds with complete transfer of valence electron(s) between atoms. It is a type of chemical bond that generates two oppositely charged ions, one is the electron donor (cation/metal) and the other is the electron acceptor (anion/nonmetal).
ionic bonds
bonds with sharing of electrons between atoms. This type of bonding occurs between two atoms of the same element (diatomic molecule) or of elements with the same electronegativity. This bonding occurs primarily between nonmetals; however, it can also be observed between cations/metals and anions/nonmetals. (e.g.
binary acids)
covalent bonds
special type of ionic compound that are covalently bonded since hydrogen acts as a cation/metal
(+1) when reacting with an anion/nonmetal
binary acids
The arrangement of electron pairs around a
central atom
- In determining the shape, it takes into account
the presence of both bond pair(s) and lone
pair(s) of electrons. - Number of total electron pairs are calculated.
electron domain geometry
The arrangement of atoms in a molecule, usually
relative to a single central atom
- It excludes lone pairs from determining a
molecule’s shape, though repulsion from lone
pair(s) is taken into account only in bond
angles. - Number of bonding pairs are only calculated.
molecular geometry
we can use the ______________ and the ________________________ when writing for the molecular geometry of a molecule or a compound.
Lewis structure, Valence Shell Electron Pair Repulsion (VSEPR) theory
a model used to predict 3-D molecular geometry based on the number of valence shell electron bond pairs among the atoms in a molecule
or ion. This model assumes that electron pairs will arrange themselves to minimize repulsion effects from one another. In other words, the electron pairs are as far apart as possible.
Valence Shell Electron Pair Repulsion (VSEPR) theory
In showing the bonds of a molecule, the ______ represents the flat on the paper position while the __________ is the one facing the
observer. The _________ is the one at the back.
line, solid wedge, dashed wedge
________ of an atom play(s) an important role
in the molecular geometry of a compound. They/it
occupy specific orbitals in the atoms, as they/it
increase the repulsion and decrease the bond angle.
lone pair
AX2
EDG: Linear
Mg: Linear
AX3
EDG: Trigonal Planar
Mg: Trigonal Planar
AX2E1
EDG: Trigonal Planar
Mg: Bent
AX4
EDG: Tetrahedral
Mg: Tetrahedral
AX3E1
EDG: Tetrahedral
Mg: Trigonal Pyramidal
AX2E2
EDG: Tetrahedral
Mg: Bent
AX5
EDG: Trigonal Bipyramidal
Mg: Trigonal Bipyramidal
AX4E1
EDG: Trigonal Bipyramidal
Mg: Seesaw
AX3E2
EDG: Trigonal Bipyramidal
Mg: T-Shaped
EX2E3
EDG: Trigonal Bipyramidal
Mg: Linear
EX6
EDG: Octahedral
Mg: Octahedral
EX5E1
EDG: Octahedral
Mg: Square Pyramidal
EX4E2
EDG: Octahedral
Mg: Square Planar
a measure of an atom’s ability
to attract shared electrons to itself.
electronegativity
On the periodic table, electronegativity generally
__________ as you move from left to right across a
period and _____________ as you move down a group.
increases, decreases
- Electronegativities can be used to predict the nature of the chemical bond that can exist between atoms.
- The larger the electronegativity difference ( EN)
between the atoms, the _______ the bond will be. - ___________ have the highest EN and are therefore the most polar of the chemical bonds.
- _____________may be polar or nonpolar depending on the electronegativities of the atoms involved.
more polar; ionic; covalent bonds
electronegativity difference greater than or equal to 1.7
ionic bonds
END greater than 0.4 but less than 1.7
polar covalent bonds
END less than or equal to 0.4
non-polar covalent bonds
Two atoms with equal electronegativities equally
share the electrons, which results in an even
electron density. This produces a ________________
non-polar bond
Unequal electronegativities result in an uneven electron distribution in a bond, with one partially positive end and one partially negative end. The resulting bond is described as ______
polar
- The charge separation resulting from the unequal sharing of electrons is known as __________ represented as arrows where the arrowhead points the more electronegative atom.
- The greater the electronegativity difference between the bonded atoms, the greater it is
bond dipole
A polar covalent molecule always contains one or
more polar bonds, but some molecules with polar
bonds can be nonpolar overall.
- This difference can be explained by the _____________ (molecular dipole) measured in debyes and which is affected by the shape of the molecule
net dipole moment
The polarity of substances determines their
solubility in different solvents.
Solubility follows the general rule “like dissolves
like,” which pertains to the similarity of the
polarity of the solute and the solvent. A nonpolar
(or polar) solute _______ dissolve in a polar (or
nonpolar) solvent.
will not
