#4 Entry- Elements and the Periodic Table

Elements, Compounds and Mixtures

For today's lesson, we touched on elements (atoms and molecules) and the periodic table (metals, non-metals and properties).

Definitions

Element: An element is a substance made of only one type of atom

Atoms: An atom is the smallest particle that retains the properties of the element

Molecule: A molecule is made up of 2 or more atoms that are chemically joined

Atoms

• Atoms retains the chemical properties of the element 
• Different atoms represent different elements
• The factors that differentiates the atoms are: size and spacing (between atoms)
• Diatomic: 2 atoms chemically joined together
• Triatomic: 3 atoms chemically joined together
• Polyatomic: 3 or more atoms chemically joined together

That is generally what we covered for atoms. More importantly is the Periodic Table.

Periodic Table

The Periodic Table is split into groups based on several criterial: metals/non-metals, number of subatomic particles (protons) and melting point boiling point etc. All these are related to the properties of the element. As seen from the periodic table above, there is a staircase line separating the elements, at   Al, Ge, Sb and Po. The elements on the left-hand side of the periodic table are the metals. The elements on the right-hand side are the non-metals. Those in the middle are called transition metals. Bordering the separation line, Sl, As etc, they are considered metalloids as they have both the characteristics of a metal and a non-metal. 

Things to note:

• When one writes the group of the elements, always use the roman numerals (eg I, II, III, IV...)
• Periods can be written using normal digits
• The elements are arranged according to increasing atomic number
• First letter of the chemical symbol must always be written in capital letters
• On the extreme right of the periodic table, are the noble gas, they are called group 0. 

Noble Gas

Noble gas is an unreactive element. It means that it does not bind to any atoms, nor does any atoms bind to it.

Lastly we went through the assignment and here are some pointers to note:

• Melting point below 25°C is considered low melting point
• High melting point: Above 100°C (in reference to water)
• Electrical Conductivity: value less than 1, considered low

Terms

Malleable: Bend easily

Ductile: Can be drawn into wires

Reflection: Today we learnt many new things such as the periodic table and more on elements. I also learnt an interesting fact, that pure metals are actually malleable! It was also interesting to learn how the periodic table works. It is really organized, and I believe we will get round it soon. 

Well, that is all for today!

Next lesson: Still on Elements, Compounds and Mixtures and the Periodic Table. 

***Experiments conducted the next lesson***