CHEMISTRY - BOHR'S MODEL & LEWIS STRUCTURE

What is the shell model?

The shell model of the atom describes the arrangement of electrons around the nucleus of an atom in terms of energy levels or shells.
The 13 electrons in an aluminum atom are arranged in three energy levels of 2.8.3

The nuclear model of the atom states an atom is composed of a positively charge nucleus which is orbited by negatively charged electrons.
The shell model of the atom describes how the electrons are arranged around the nucleus.
Three basics points will help you understand the arrangement of electrons around the nucleus of an atom.

1. The Atomic Number (number of protons) = The number of electrons in an atom.
2. The maximum number of electrons in the outer shell is eight
3. The maximum number of electrons in the inner shells is 2n² where n = the shell number

Shell number, n	1	2	3	4	5
Maximum number of electrons in shell, 2n2	2	8	18	32	50

The Atomic Number of an element can be found from any Periodic table.
For example the Atomic number of the element Bromine is 35. 

Bromine therefore has 35 protons and 35 electrons.

The electron configuration of bromine is 2.8.18.7 which means there are 2 electrons in the first shell, 8 electrons in the second shell, 18 electrons in the third shell and 7 electrons in the fourth shell. The total number of electrons is 35.

CHEMISTRY - PERIODIC TABLE - TRANSITION METALS #7

TRANSITION METALS

Transitioning

Let's start off by telling you that there are a lot of elements that are considered transition metals. 
Which metals are the transition metals? 

• 21 (Scandium) through 29 (Copper)
• 39 (Yttrium) through 47 (Silver)
• 57 (Lanthanum) through 79 (Gold)
• 89 (Actinium) and all higher numbers.

What Makes Them So Special?
It all has to do with their shells/orbitals. 
Transition metals are good examples of advanced shell and orbital ideas. 

• They have a lot of electrons and distribute them in different ways. You will usually find that transition metals are shiny, too. Not all of them, but we are sure you've seen pictures of silver (Ag), gold (Au), and platinum (Pt). 

Transition metals are able to put more than eight electrons in the shell that is one in from the outermost shell. Think about argon (Ar). It has 18 electrons set up in a 2-8-8 order. 
Scandium (Sc) is only 3 spots away with 21 electrons, but it has a configuration of 2-8-9-2. Wow! This is where it starts. This is the point in the periodic table where you can place more than 8 electrons in a shell. You need to remember that those electrons are added to the second-to-last shells. 

The transition metals are able to put up to 32 electrons in their second-to-last shell. Something like gold (Au), with an atomic number of 79, has an organization of 2-8-18-32-18-1. Of course, there are still some rules. No shell can have more than 32 electrons. You will find it's usually 2, 8, 18 or 32 for the maximum number of electrons in an orbital. 

One More Thing

Most elements can only use electrons from their outer orbital to bond with other elements. Transition metals can use the two outermost shells/orbitals to bond with other elements. It's a chemical trait that allows them to bond with many elements in a variety of shapes. 
Why can they do that? As you learn more, you will discover that most transition elements actually have two shells that are not happy. Whenever you have a shell that is not happy, the electrons want to bond with other elements. Example: Molybdenum (Mo), with 42 electrons. The configuration is 2-8-18-13-1. The shells with 13 and 1 are not happy. Those two orbitals can use the electrons to bond with other atoms. 

PHYSICS - ELEMENT of the DAY - CARBON

ELEMENT of the DAY - CARBON

Carbon is an element that has been known since ancient times. Carbon sometimes is considered the element of life, since all living cells and organic molecules contain carbon. Carbon takes the form of one the hardest elemental substances (diamond) and one of the softest (graphite). You encounter pure carbon as diamond, graphite in pencil 'lead', and amorphous carbon in soot and charcoal. The element is found in the food you eat, the clothes you wear and the air you breathe.  
Ten facts about Carbon:

1. Carbon is the basis for organic chemistry, as it occurs in all living organisms.
2. Carbon is a nonmetal that can bond with itself and many otherchemical elements, forming nearly ten million compounds.
3. Elemental carbon can take the form of one of the hardest substances (diamond) or one of the softest (graphite).
4. Carbon is made in the interiors of stars, though it was not produced in the Big Bang.
5. Carbon compounds have limitless uses. In its elemental form, diamond is a gemstone and used for drilling/cutting; graphite is used in pencils, as a lubricant, and to protect against rust; while charcoal is used to remove toxins, tastes, and odors. The isotope Carbon-14 is used in radiocarbon dating.
6. Carbon has the highest melting/sublimation point of the elements. The melting point of diamond is ~3550°C, with the sublimation point of carbon around 3800°C.
7. Pure carbon exists free in nature and has been known since prehistoric time.
8. The origin of the name 'carbon' comes from the Latin word carbo, for charcoal. The German and French words for charoal are similar.
9. Pure carbon is considered non-toxic, although inhalation of fine particles, such as soot, can damage lung tissue.
10. Carbon is the fourth most abundant element in the universe (hydrogen, helium, and oxygen are found in higher amounts, by mass).

ELEMENT of the DAY - OXYGEN

ELEMENT of the DAY - OXYGEN

Oxygen is an element you can't live without, although too much could make you sick or dead. Oxygen is in the air you breathe, the water you drink, most rocks and thousands of compounds. The element is inside of you and all around you. How much do you know about it?
Here are 10 interesting facts about the element oxygen. 

1. Animals and plants require oxygen for respiration.
2. Oxygen gas is colorless, odorless, and tasteless.
3. Liquid and solid oxygen are pale blue.
4. Oxygen is a non-metal.
5. Oxygen gas normally is the divalent molecule O2. Ozone, O3, is another form of pure oxygen.
6. Oxygen supports combustion.
7. Oxygen is paramagnetic.
8. Approximately 2/3 of the mass of the human body is oxygen.
9. Excited oxygen is responsible for the bright red and yellow-green colors of the aurora.
10. Oxygen was the atomic weight standard for the other elements until 1961 when it was replaced by carbon 12.