February 09, 2020
(Atomic Number) The number of protons in the nucleus of an atom. Also called the proton number. The higher the atomic number, the heavier the atom is. Atomic Mass=Mass of Protons + Mass of Neutron.
the elements are arranged in order of increasing atomic number the horizontal rows are called periods the vertical columns are called groups elements in the same group are similar to each other The main groups are numbered from 1 to 7 going from left to right and the last group on the right is group 0 The section in the middle of the table is called the Transition Metals. If you know what one of the elements in a group is like, you can make predictions about the other elements in a group. all the elements in group 1 are reactive metals and all the elements in group 0 are unreactive non-metals. The zig-zag line in this diagram separates the metals, on the left, from non-metals, on the right. Hydrogen is a non-metal but it is often put in the middle. Notice that most elements are metals, rather than non-metals. Each element has its own chemical symbol, made from letters. Remember that you will only find elements in the periodic table and never compounds. (So you won’t find substances like water or copper sulphate in the periodic table) You can accurately predict that Potassium it will have the lowest melting point, the highest density and the highest reactivity of all the elements in group 1. In a neutral atom, the number of protons and electrons is the same. Reaction between Acid and Alkali produce Salt and water.(Locate acid and alkali from the table) Reaction between metal and oxygen form oxide.
Resources others found helpful
A comprehensive review of Spanish tenses
This sit is available for different levels. It will help the student to increase his level with collaboration of the tutor