1. By Jeffrey medina

2. Some elements have no color. John Newland was the person who came up with the idea of arranging the elements in a table, hence periodic table. But Dmitri Mendeleev was the person who created the first periodic table from the 63 known elements at that time. A horizontal row in the periodic table is called a period, while a horizontal column on the periodic table is called a group.

3. The main group of elements on the periodic table have diverse uses and also diverse properties. Group 1 on the periodic table is made up of Alkali metals. Group 2 is made up of Alkaline-earth metals while the 17 group is made up of Halogens which are extremely reactive. Even though hydrogen is the most common element in the world, it is separated in a class by itself. Metals can be mixed with other metals to make an alloy.

4. When atoms have an equal amount of protons and electrons, they are electrically neutral. As you move down a group on the periodic table, there are more electrons in the energy level between the nucleus and outermost electrons. When you move from one period on the table to the next, the # of protons and electrons increases by one. The volume occupied by the electrons around the nucleus determines the size of the atom. Also electron shielding also determines the atomic radius.

5. The atomic radius in a periodic table decreases as you move across a period and increases as you move down a group. Electronegativity- a scale of numerical values that reflects how much an atom in a molecule attracts electrons. Linus Pauling came up with electronegativity. Electronegativity increases as you move across a period, and decreases as you move down a group. Noble gases have a very low melting and boiling point.

6. The natural elements are carbon, hydrogen, oxygen, nitrogen, phosphorus, and finally sulfur. The simplest nuclear reaction is fusing hydrogen nuclei to form helium. In the middle ages many early chemists tried to change ordinary metals into gold. Synthetics elements