PERIODS
The periodic table includes seven horizontal rows called periods. Elements within the same period will have the same amount of occupied energy levels (Myer, Tocci, Oldham 122). That being said, the first row has one occupied level, the second row has two levels, and so on until you get to the seventh row.
VALENCE ELECTRONS
Valence electrons are the electrons that occupy the outermoist energy level of an element. They also have the highest amount of energy and are the furthest away from the nucleus. The electrons in the highest level are only single digits, meaning groups 13-18 use their last digit as their valence electron number. Since the number of valence electrons depends on the element's group, the following families have the set number of electrons in their outermost shell:
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The Hydrogen Family = 1
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The Alkali Metals = 1
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The Alkaline Earth Metals = 2
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The Transition Metals = 2 due to them having two valence electrons, when their electron configurtions are written, in their groups. (Ex. Cobalt: [Ar] 4s^2 3d^7. Cobalt is in the fouth period so you would take the electron number from 4s^2 and say it is the amount of valence electrons in that element).
GROUPS
There are twelve groups within the modern periodic table. These groups are composed of elements that all have similar chemical and physical properties, including the amount if valence electrons. They also have the same number of valence electrons.The ten gorups are...
1. Hydrogen ...which only contains hydrogen and is mainly used to fill ballons.
2. The Alkali Metals (lithium, sodium, potassium, rubidium, cesium, and francium.) These metals are very reactive and always combine with other things in nature. For example, sodium combines with chlorine to make salt. Fun fact: the Alkali metals are soft enough to cut with a butter knife.
3. The Alkaline Earth Metals (beryllium, magnesium, calcium, strontium, barium, and radium.) The alkalines are also reactive metals that combine with other nonmetals in nature. Some of the elements in this group are important sources of mineral nutrients including calcium and magnesium.
ORBITALS
An orbital is the region of space around the nucleus where electrons are liekly to be found. The periodic table houses four orbitals: the s, p,d, and f blocks. These blocks all contain different groups of elements.
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The S block elements: The Hydrogen group, The Alkali Metals, and the Alkaline Earth Metals.
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The P block elements: The Boron Group, the Carbon Group, the Nitrogen Group, the Oxygen Group, the Halogens, and the Noble Gases.
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Elements in the D block: The Transitiion Metals.
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Elements in the F block: The Inner Transition Metals, or the Lanthanides and Actanides.
The orbitals have been further divided into priniciples and rules for better organization. This organization is also built off of quantum numbers, or number that specify the properties of electrons.
4. The Transition Metals (elements in the third column to elements in the twelfth column.) Transition metals are less reactive than the previous three groups and are harder metals. They are used for construction, producing jewlery, and "as metals."
5. The Boron Family are elements in the thirteenth cloumn including boron (duh), aluminum, gallium, indium, and thallium. Some uses of this family include Boron being an agent in borax and boric acid. Aluminum on the other hand is the third most common element in the earth's crust.
6. The Carbon Family is composed of elements of the fourteenth group. This family consists of elements that are significantly important to computers and life. The basis for the entire branch of chemistry is within this group, carbon. It also has vital semiconductors like silicon and geranium.
7. The Nitrogen Family includes elements in group fifteen (nitrogen (again, duh) phosphorus, arsenic, antimony, and bismuth.) Nitrogen is an extremely critical resource that makes up 75% of the atmosphere, although, most of the world's nitrogen is not available to living things. Phosphorus is also important to living things and can be commonley be found at the end of a match.
8. The Chalcogens, or the Oxygen Family, is comprised of the elements from group sixteen (oxygen, sulfur, selenium, terrurium, and polonium.) Certain components from this family, like oxygen, are needed for respiration. Others, like sulfur, give off a very distinct smell that can be emitted from water, a skunk, or garlic.
9. The Halogen Family is made up of elements from the seventeenth column (flourine, chlorine, bromine, iodine, and astatine). These elements are very reactive, diatomic, nonmetals that are always combined with other elements in nature. The components of this group are used in disinfectants and to strengthen teeth.
10. The Noble Gases are column eighteen on the periodic table (helium, neon, argon, kryton, xenon, and radon) and are monoatomic and do not bond with other elements and have a full outershell due to them having eight valence electrons. They are used in blimps and "neon" signs.
11. The Lanthanides are elements located at the bottom of the periodic table (cerium, prasedoymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium.) The Lanthanides are known for creating an alloy of cerium and iron to produce the "flint" used in gas and cigarette lighters.
12. Last, but certainly not least, is the second group at the bottom of the periodic table, the Actinides. The Actanides are the elements thorium, protactinium, uranium, neptunium, plutonium, americium, curium, berkelium, californium, einsteinium, fermium, mendelevium, nobelium, and lawrencium. Elementa like plutonium and uranium are used to make atom boms, while other actinides are used in cancer therapy for their radioactive properties.
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The Boron Family = 3
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The Carbon Family = 4
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The Nitrogen Family = 5
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The Chalcogens = 6
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The Halogens = 7
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The Noble Gases = 8
Quantum numbers are positive integers that determine the main energy level occupied by the electron in an element. Angular momentum quantum numbers (l) are the sublevels of these main energy levels. For example, I = 0, 1, 2, or 3. This corresponds the the sublevels s (0), p (1), d (2), and f (3). Next are spin quantum numbers, which indicates the electron's orientation being reprented by opposite arrows. This is how we know that a single orbital can only hold up to two electeons of opposite spins.
In 1925, a German chemist named Wolfgang Pauli created something called Pauli's exclusion principle, which states that two electrons from the same class cannot fill the same orbital. this principle is mainly used to hekp one write an electron configuration. The next rule is the Aufbau principle, or having an electron occupy orbitals, starting with the lowest energy level first and then moving up. This means the configuration would now go in sequential order. The last principle associated with orbitals is Hund's rule works to produce an element's orbitals notation . This rule implies that electrons have to fill each orbital singly before any orbitals get a second electron. Hund's rule helps more with drawing out how the amount of electrons fill each subshell.