Chemistry chapter 6 review

An ionic bond results from electrical attraction between
cations and anions.
A non-polar covalent bond is unlikely when two atoms of different elements join because the atoms are likely to differ in
electronegativity
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Bond length is the distance between two bonded atoms at
their minimum potential energy.
to draw a Lewis structure, it is not necessary to know
bond energies.
For multiple covalent bonds to form in molecules, the molecules must contain carbon, nitrogen, or
oxygen.
The principle that states that atoms tend to form compounds in which each atom has eight electrons in its highest occupied energy level is called the..
octet rule.
An example of a molecule that cannot be represented adequately by a single Lewis structure is
O₃
Lattice energy is an indication of the
strength of an ionic bond.
A covalent bond in which the bonded atoms have an unequal attraction for the shared electrons is called a(n):
Polar Covalent Bond
A molecule containing two atoms is called a(n)…
Diatomic Molecule
The degree to which bonding between atoms of two different elements is ionic or covalent can be determined from the differences in the… _______ of the elements.
Electronegativities
A neutral group of atoms held together by covalent bonds is called a(n)…
Molecule
The electron dot notation for a hydrogen atom is
A shorthand representation of the composition of a substance using atomic symbols and numerical subscripts is called a(n)…
Chemical Formula
A charged group of covalently bonded atoms is called a(n)…
Polyatomic Ion
A covalent bond between two atoms produced by sharing two pairs of electrons is called a(n)…
Double Bond
The simplest collection of atoms from which the formula of an ionic compound can be established is called a(n)…
Formula Unit
The energy required to break a chemical bond and form neutral isolated atoms is called
Bond Energy
A chemical bond that results from the attraction between metal atoms and the surrounding sea of electrons is called a(n)
Metallic Bond
The property of being able to be drawn, pulled, or extruded through a small opening to produce a wire is called
Ductility
carbon dioxide (CO2)
Linear
methane (CH4)
Tetrahedral
the nitrate ion [NO3]-
Trigonal-planar
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Define chemical bond.
A mutual electrical attraction between the nuclei and valence electron of different atoms that bind the atoms together.
Explain why most atoms form chemical bonds
To try to get to a state of lower potential energy.
Describe ionic and covalent bonding.
Ionic Bond – an attraction between positive and negative ions (cations and anions)
Covalent Bonding – the sharing of electrons between two or more atoms.
Explain why most chemical bonding is neither purely ionic nor purely covalent.
To be purely covalent, the electronegativity must be the same, and they all have different ones. The only way to have a purely covalent bond is to have the same two atoms bonded together. (Two hydrogen together.)
To be purely ionic, one of the atoms has to have a zero amount of electronegativity, which does not exist.
all atoms have…
All atoms have at least some attraction.
Classify bonding type according to electronegativity differences.
Less than 0.3 – Nonpolar Covalent
Between 0.3-1.7 – Polar Covalent
Greater than 1.7 – Ionic Bonding.
Define molecule
A neutral group of atoms that are held together by covalent bonds.
Define molecular formula
A formula for substances that exist as molecules.
molecular formula tells us….
Tells us the types and numbers of atoms combined in a single molecule of a molecular compound.
Explain the relationships between potential energy, distance between approaching atoms, bond length, and bond energy.
Two atoms far apart being brought closer to each other, their potential energy decreases until the nuclei repel each other (the repulsion). The nucleus of one atom is attracted to the electrons of the other atom. As the distance gets less, the potential energy gets less.
The shorter the bond, the greater the bond energy.
State the octet rule.
Chemical compounds tend to form so that each atom, by gaining, losing or having electrons, ahs an octet of electrons in its highest occupied energy level (8)
Exceptions:
Boron – has 3 electrons, but even with sharing, can only get to 6.
Hydrogen – has 1 electron, first level only has 2.
Beryllium – 2 electrons, most it can get is 4.
List the six basic steps used in writing Lewis structures.
Get the electron dot for each one – write the letter of the element in the middle, look at the number of valence electrons. Arrange your dots (father, son, holy spirit order. Just keep it consistent. Each of the four corners has to get a dot before getting a second).
Explain how to determine Lewis structures for molecules containing single bonds, multiple bonds, or both.
Two single electrons join together to form a shared pair. Leftover single atoms can join to form a double bond
Nitrogen
has 3 singles, but 2 atoms. End up dragging in between to form a triple bond.
Explain why scientists use resonance structures to represent some molecules.
Resonance structures show the average, and neither structure accurately represents it
Compare and contrast a chemical formula for a molecular compound with one for an ionic compound.
They both tell us how many elements and how many there are of each.
In molecular, the actual number of atoms of each is shown. In ionic compounds, it only tells us the lowest whole number ratio
Discuss the arrangements of ions in crystals.
Next to every negative has to be a positive ion. The arrangement is so that there will be no two positives or no two negatives next to each other.
The total positive should equal the negative so it shall stay neutral.
Define lattice energy and explain its significance
Energy required to break the positive and negative ions apart. ___ The higher the lattice energy, the stronger the bonds and the higher the boiling/melting points.
List and compare the distinctive properties of ionic and molecular compounds.
-Ionic compounds are made of ions; molecular compounds are made of molecules
-Ionic compounds at room temperature are solids; molecular compounds at room temperatures are gases and liquids
-Ionic compounds don’t conduct electricity in a solid, but they do when they’re melted or dissolved; Molecular compounds in the pure form do not conduct electricity.
Describe the electron-sea model of metallic bonding, and explain why metals are good electrical conductors.
Like a crystal lattice, but there’s a sea of electrons. Take a few elecctrons away, and you have an anion. They are free to move around.
Metals are good conductors of electricity – the flow of charges – electrons because…..
Since the electrons are free to move around, they have good flow, and are therefore good conductors.
Explain why metal surfaces are shiny.
They have partial and vacant orbitals where electrons can jump to (jump out, absorb energy, fall back, release energy).
Explain why metals are malleable and ductile but ionic-crystalline compounds are not.
Metals are malleable (able to be hammered easily into thin sheets) and ductile (ability to draw it out into a wire) because the bonds are not very directional or strong.
Ionic-crystalline compounds…
every positive has to be with a negative, so it is not malleable or ductile because they have very strong bonds. They are also very directional. It would not pound into a flat sheet, but pulverize because it would break all the bonds.
Explain VSEPR theory.
Valence Shell Electron Pair Repulsion Theory.
Valence electrons repel …
they want to get as far apart as they can in the atom.
Using this concept helps us explain the shape of the molecule.
Explain how the shapes of molecules are accounted for by hybridization theory
We hybridize orbitals – S and P only.
All orbitals formed by hybridization have equal energy.
Describe dipole-dipole forces
One end has a positive, and the other one is negative. In this case, both are dipoles.
Use electronegativity to figure it out.
Describe hydrogen bonding
Extra strength bonding equals a higher boiling point.
Describe induced dipoles
Where you have a polar molecule inducing a non-polar molecule to behave like a dipole.
Describe and London dispersion forces
Intermolecular attractions resulting from consistent motion of electrons and the creation of instantaneous dipoles.
Acts between all atoms and molecules.
Are the only intermolecular forces acting among noble-gas atoms, nonpolar molecules, and slightly polar molecules.
Explain what determines molecular polarity.
Electronegativity and molecular geometry
VSPER CHART
BeF2 – sp – Ab2 – Linear
BF3 – sp2 – Ab3 – Trigonal-Planar
CH4 – sp3 – Ab4 – Tetrahedron
NH3 – Ab3E – Pyramid
H3O – Ab2E2 – Bent
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