The same concept holds true for nitric acid and, in this case, the charge is evenly distributed among the 3 oxygen atoms in the nitrate anion.
This makes the negative charge less available for the reverse reaction and helps explain why nitric acid is a fa
Balancing Chemical Equations Chemical equations must be balanced with respect to all atoms and the atoms must exist in real compounds.
Balance equations by using the following rules. 1. Select the compound with the largest number of atoms of an element no
The convention of writing acids always places the acidic hydrogen atoms first in the formula. Therefore you will always know that HF (aq), HCl (aq), HBr (aq), HI (aq) and nitric acid, HNO3, all have 1 acidic hydrogen atom. Sulfuric acid, H2SO4, has 2 acid
The Periodic Table The modern periodic table is a device scientists use to organize the elements with respect to the atomic numbers of the elements rather than the mass. The atomic number also relates to the orbital arrangement of the electrons of the ele
The atomic mass is given by the number below the symbol. The atomic mass that is given is not a whole number due to the existence of isotopes for the elements.
Those elements, which exhibit characteristics of metals, are colored white in the following per
Those elements that are considered nonmetals are colored yellow. Those nonmetals that are the inert gases are colored light blue. The elements that are colored green are called metalloids and have some of the properties of metals as well as some of the pr
Compounds Atoms of the same or different elements can combine in set proportions to form compounds. The proportions are determined by the numbers of electrons shared or exchanged between elements. This combining power of elements is most readily learned b
Naming Ionic Compounds We can learn the nomenclature of common ionic inorganic compounds by memorizing the following tables of common ions. Sometimes clusters of atoms are called groups and we learn a charge for the group as a whole. The order of the lett
Naming Molecular Compounds Most elements can be drawn by just using the symbols. However, the most stable form for many elements is a compound rather than the individual atom. The most common examples of these binary (2 atom) compounds are shown in the fo
When a hydrogen atom forms compounds with the nonmetals, the hydrogen atom is named first and the nonmetal is named as if it were a negative ion.
hydrogen fluoride.The (g) for (gas state) must be shown since HF in a solution of water is called hydrofluori
Never use the mono prefix for the first element and always use a prefix for the second element.
CO NO N2O PCl3 CCl4 carbon monoxide nitrogen monoxide dinitrogen monoxide.laughing gas phosphorus trichloride carbon tetrachloride
Deciding Which Nomenclature
Transfer of Thermal Energy A common unit of energy is the calorie. A calorie is defined as the amount of heat that is needed to raise the temperature of one gram of water one degree centigrade. Modern convention uses a unit of energy called a joule. A cal
T and q can have either negative or positive signs and Csp will always have a positive sign. The convention used is "q" has a positive value if heat is added to the substance from its surroundings and a negative value if the substance loses heat to its s
Changes of Physical State When the physical state of a substance is changed, heat is either absorbed or liberated but the temperature remains constant. The heat required to melt ice without any increase in the temperature of the system is equal to 80 calo
Let's see how this works by doing some examples. 1. First draw the electron-dot formula. 2. Then determine the hybridization needed for the number of groups attached to the central atom. 3. Now draw the 3-dimensional shape corresponding to that hybridizat
Electron-Pair Geometry and Molecular Geometry Now for a discussion about the shape of molecules! Why should you learn two ways to describe the geometry. When we experimentally look at molecules, we see how the atoms are arranged but don't see the non-bond
Hybridization of Atomic Orbitals and the Shape of Molecules
If the four hydrogen atoms in a methane molecule (CH4) were bound to the three 2p orbitals and the 2s orbital of the carbon atom, the H-C-H bond angles would be 90o for 3 of the hydrogen atoms an
The valence shell electron-pair repulsion model (VESPR) was devised to account for these molecular shapes. In this model, atoms and pairs of electrons will be arranged to minimize the repulsion of these atoms and pairs of electrons. Since the non-bonded e
In the case of methane, the three 2p orbitals of the carbon atom are combined with its 2s orbital to form four new orbitals called "sp3" hybrid orbitals. The name is simply a tally of all the orbitals that were blended together to form these new hybrid or
These hybrid orbitals have 75% p-character and 25% s-character which gives them a shape that is shorter and fatter than a p-orbital. The new shape looks a little like.
A stick and wedge drawing of methane shows the tetrahedral angles.(The wedge is coming
In the case of ammonia, the three 2p orbitals of the nitrogen atom are combined with the 2s orbital to form four sp3 hybrid orbitals. The non-bonded electron pair will occupy a hybrid orbital. Again we need a hybrid orbital for each atom and pair of non-b
In the case of water, the three 2p orbitals of the oxygen atom are combined with the 2s orbital to form four sp3 hybrid orbitals. The two non-bonded electron pairs will occupy hybrid orbitals. Again we need a hybrid orbital for each atom and each pair of
Now let's look at something a bit different. In the boron trifluoride molecule, only three groups are arranged around the central boron atom. In this case, the 2s orbital is combined with only two of the 2p orbitals (since we only need three hybrid orbita
Finally let's look at beryllium dichloride. Since only two groups are attached to beryllium, we only will have two hybrid orbitals. In this case, the 2s orbital is combined with only one of the 2p orbitals to yield two sp hybrid orbitals. The two hybrid o
Hybridization Involving d-Orbitals
As we discussed earlier, some 3rd row and larger elements can accommodate more than eight electrons around the central atom. These atoms will also be hybridized and have very specific arrangements of the attached groups
Summary of Hybridization.In the following summary, groups are considered to be atoms and/or pairs of electrons and hybrid orbitals are the red lines and wedges. When the octet of an element is exceeded, then hybridization will involve dorbitals. Unhybridi
Hybridization Involving Multiple Bonds
Only a maximum of two electrons can occupy any orbital whether it is an atomic orbital or a molecular orbital due to electron-electron repulsion. When we draw a double or a triple-bond between two atoms, we imply tha
In the molecule C2H4, ethene, both carbon atoms will be sp2 hybridized and have one unpaired electron in a non-hybridized p orbital.
These p-orbitals will undergo parallel overlap and form one pi bond with beanshaped probability areas above and below the
The 3-dimensional model of ethene is therefore planar with H-C-H and H-C-C bond angles of 120o.the pi-bond is not shown in this picture.
Now let's look at H2C2 (acetylene). Both carbon atoms will be sp hybridized and have one electron in each of two unhyb
Nuclear Chemistry The nuclei of most naturally occurring elements are very stable in spite of the fact that the protons in the nucleus repel each other because of electrical repulsion. Some nuclei with certain ratios of neutrons to protons and nuclei with