How To Read The Periodic Table
Learn the foolproof way of reading the periodic table. Videojug presents it to you in this video with a science teacher from Greater London Tutors.
Hi, I'm Donald Sinclair. I'm a science teacher with Greater London Tutors, and today we're going to be looking at a few topics in chemistry. The periodic table is in essence a list of every known atom.
Everything that exists or had existed or will exist is made up of a combination of bearing amounts of these atoms. You can think of it as like the ingredient list for the universe. The way it is ordered is it allows us to predict how different chemicals will react, even some allows us to predict the chemical properties of elements that have not yet been discovered.
The periodic table is arranged from left to right starting at the top left. It's arranged in order of the atomic number. Atomic number is how many protons are in an atom of that element.
So for example, oxygen has an atomic number of 8 because one atom of oxygen contains 8 protons. If I had 9, it wouldn't be oxygen anymore. As well as being arranged in order of atomic number, the elements are going through new periods every so often.
It wraps around starting from the next line below. This is not arbitrary; this is a consequence of how electrons are arranged within an atom. Electrons in an atom fill up in shells.
The first shell can take 2 electrons, the second shell can take 8, the third can take 8 and so on and so forth. Although it gets a bit more complicated later on, this explains the lens of the first few rows of the first three periods. That's why the first rows are nicotine, hydrogen and helium, the second and third rows only contain 8 elements.
By doing it this way, it is found that the columns in the periodic table which are called groups, all share similar chemical properties. For example, the first group, group 1 which is also sometimes called the alkaline metals, contain elements like sodium, potassium and rubidium and so forth. All these chemicals have chemical properties.
There are all metallic, there are all very soft that you can cut it even in a knife. There are very reactive with water, so on and so forth. Similarly for elements here in group 7, the helium elements which are all sharing with non-metals.
The metals in the periodic table are to be found on the left, the non-metals are on the right. As well as sharing similar chemical properties in a group, the chemical properties and physical properties are addressed in one way or the other as you go down or up the group. For example, returning to the alkaline metals, as you progress on group 1, sodium, potassium and so forth, the chemical reaction increase in activity.
Therefore, something like caesium, not on the group, is much more reactive than sodium on the top. Similarly, physical properties can also change as you go down the group. The halogens which are currently on the top, start off as light gases, light hollowed gases at the top progressing into darker solids as you go down.
Finally, there are sections of the periodic table which arises as a result of more complicated electron layers in the outer shells. The transition metals, which is a large group of metals found in the center all share very similar chemical and physical properties. They're generally non reactive but they are generally quite hard, strong, shiny and polished and good conductors of heat and electricity.
Similarly the lactinide and actinides are sort of squeezed in between two elements as a result of complicated electron layers. The periodic table is growing as new elements are created and discovered. The first 92 elements are naturally occurring in nature, everything from up to radium.
From element 93, the neptunium, these have to be created artificially in nuclear reactions. First of which, neptunium was created in 1939. An entry on the individual element means its symbol, helium for example has the symbol He, its atomic number which will be number of protons in the element and its mass number.
The mass number is the number of protons in the atom plus the number of neutron