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Chemistry 10th Grade

Chapter 8 Test

models used to indicate the molecular shape ball and stick models
what does the ball represent the atom's nucleus and inner level electrons
what do the straight sticks represent single bonds
what do the curved springs represent multiple bonds
The shapes of the molecule must be symmetrical
What does symmetrical mean in this case the bonds and atoms must be in a regular pattern with equal distances separating the atoms that are not bonded to each other
why are they arranged symmetrically because it is based on the valence electrons which have the same charge and same charged particles repel each other
what is the VSEPR theory It is the valence shell electron pair repulsion theory
what is the theory of the VSEPR theory in small molecules, the pairs of valence electrons are arranged as far apart from each other as possible
Molecules that contain _____________________ do not follow the VSEPR theory transition metals
Molecules that contain only 2 atoms are connected in what pattern or form Linear
Are all linear molecules made of just two atoms No, some contain three such as CO2
we can discuss the ways bonds are arranged by looking at the the ______ ________ bond angles
What are bond angles the geometric angle between 2 adjacent (next to each other) bonds
a straight line has a bond angle of 180 degrees
a molecule that is trigonal planar has what shape a flat triangle shape
a tetraheral shape has how many sides four
what shape does a water molecule have bent
sometimes when one atom approached another atom, the orbitals may be perturbed or changed and the orbitals of the two mix and form a hybrid orbital
in a linear molecule, when a hybrid orbital is formed, what two orbitals are mixed and what is it now called the S and the P orbitals mix and it is called a SP orbital
in a trigonal planar molcule the mixing of orbitals involve what orbitals the S orbital and two P orbitals called the SPsquared orbital
in the ball and stick models, the molecules are drawn with all the sticks being the same size...is this true in real life molecules No..the bonds may have different lengths
as you move down a group in a periodic table, what happens to the bonds they get longer
multiple bonds are longer or shorter than single bonds shorter
why are the bonds shorter in multiple bonds there are more electrons and because of this, they have a stronger electrical bond to the nuclei
what are the 5 common shapes of molecules Linear, trigonal planar, tetrahedral, pyramidal, and bent
polar bonds are also known as dipoles because they have two charged ends
molecules composed of one kind of atom are nonpolar molecules
to determine whether a molecule is polar you can look at the ________ of the molecule shape
CO2 is made of polar bonds but is not a polar molecule, why? because the positive charge is in the middle of the three atoms and both poles (ends) are negative
Water is a polar molecule because its shape is _______ which gives it a positive and negative end bent
the shape of a small molecule helps to determine the molecules polarity but what happens in a large molecule the polarity determines the shape (opposite of small molecule)
what 2 things determine the polarity of a molecule the polarity of its bonds and the shape
These are properties of a substance that result from forces between molecules intermolecular forces
the type and strength of these forces determine what about a substance is it a gas, liquid , solid and will it dissolve in water or another solvent
what two forces affect the boiling points of substances molecular weight and intermolecular forces
Intermolecular forces can be divided into 3 categories...they are dipole-dipole, London forces and hydrogen bonds
when are dipole-dipole present only between polar molecules
which force affects every type of molecule London forces
hydrogen bonds are only present between molecules containing certain types of_________________________ polar bonds
dipole molecules have positive and negative charged ends because of what unequal sharing of electrons in covalent bonds
forces between neighboring polar molecules due to the attraction of oppositely charged ends are called _________ and are present in all polar molecules dipole-dipole forces
Hoe come dipole-dipole forces are not as strong as ionic bonds they do not have the "full charges" like ionic compounds do
as the polarity of molecules increase, what else increases the boiling point
Generally, the more polar the molecule, the greater the ________________, the higher the boiling point dipole-dipole force
for atoms or molecules in the gaseous state to condense to the liquid state, there must be a force of attraction between the atoms or molecules, this is called___________________________ London Forces
Who came up with this theory Fritz London in 1930
London forces are the only type of intermolecular force that affects______________________ nonpolar molecules
nonpolar molecules do not have neg and pos ends but have a uniform electron density and charge. This uniformity is an average but there are brief times the electrons are not uniform but are distorted or deformed and the molecule becomes a dipole--meaning one end has a slight but quick negative charge and the other has a slight but quick positive charge
when these dipoles happen in non polar molecules they are quick and attract each other with a London force---and it is very weak
Because they occur because the electron cloud is distributed or "dispersed", London forces are also called dispersion forces
the more easily an electron cloud is distorted is a property called polarizability
the more polarizability the greater the strength of the London forces
If the molecular size increases, what happens to the London Force it is stronger
boiling points for similar compounds tend to _________ with the molar mass because the intermolecular forces are stronger increase
when an atom such as oxygen, nitrogen or fluorine pulls the electrons away from hydrogen, the hydrogen becomes positive and the other atom becomes negative. they form a hydrogen bond
The hydrogen bond causes dipoles to be unusually strong
a hydrogen bond is not an actual true bond but it is a strong intermolecular force
hydrogen bonds are only _____ to _______ percent as strong as a covalent bond 5 to 10 percent
hydrogen bonds are much ___________________ than other intremolecular bonds stronger
how are hydrogen bonds represented in a drawing dashed lines between molecules
hydrogen bonds are very important. the properties of ______ and _____, the structure and function of _________ and _____ are due to hydrogen bonds water and ice proteins and DNA
solids are classified into 2 types amorphous solids and crystalline solids
solids that have no ordered arrangement or pattern for the particles that compose them are called amorphous solids
solids that are arranged in a regular and repeated three dimensional pattern crystalline solids
amorphous solids do not have a what definite melting point...examples, butter, glass, tar..but they become viscous (syrupy)
crystalline solids have a definite boiling point
the simplest repeating unit in a crystal is called unit cell
if you extend the unit cell in 3 dimensions, it results in definite angles and specific planes--sort of like wallpaper
a crystal has how many different type of classifications 7---cubic, tetragonal, hexagonal, rhombohedral, orthorhombic, monoclinic, triclinic
the simplest classification to study is the cubic
ionic bonds hold what together ionic solids
metallic bonds hold what together metals
intermolecular bonds hold what together molecular compounds
the simple cubic is the basic unit cell..what are the other 2 arrangements derived from it body centered cubic (bcc)and face centered cubic (fcc)
which one packs the most atoms into the smallest space the face centered and it is also called the "cubic close packing"
not all crystals have a cubic arrangement, another one that is extremely common is the hexogonal arrangement called hexagonal close packing (hcp)
many metals such as titanium and magnesium have what type of structure hexagonal close packing
in the body centered cubic (bcc) each atom has _____identical neighbors 8
the face centered cubic (fcc)and the hexagonal close packed (hcp) allow how many identical neighbors 12
the fcc and the hcp has about how much of its volume occupied by atoms 74%
the bcc has about how much of its volume occupied by atoms 68%
the simple cube has about how much of its volume occupied by atoms 52%
Created by: Wrksmarter