1. Organizing elements Periodic table

2. Mendeleev developed a periodic table that arranged elements in order of increasing atomic mass. He studied the melting point, density,color and atomic mass Atomic mass is the average mass of all the isotopes of an element Isotopes are different forms of the same element Mendeleev discovered that when he arranged the elements in order of increasing atomic mass their properties repeated regularly

3. Mendeleev created the first periodic table in 1869.A periodic table is an arrangement of elements showing the repeating patterns of their properties. Periodic means “ in a regular,repeated pattern”. He grouped elements with similar properties

4. What information does a periodic table contains Atoms are made of smaller parts At the center of an atom is the nucleus The nucleus contains positively charged particles called protons. Every atom of the same element has the same number of protons called the atomic number. The nucleus also contains particles called neutrons that have no charge. Moving around in the space outside the nucleus are negatively charged particles called electrons.

5. Four pieces of information are included in each element square of the periodic table: the atomic number, the chemical symbol, the name, and the atomic mass of the element. Atomic number is the number of protons in the nucleus of an atom. From the periodic table what you know about the structure of an atom of a particular element is its number of protons and its number of electrons

6. An element’s properties can be predicted from its location in the periodic table. The properties change in a predictable way according to atomic number The periodic table is arranged in rows called periods, and in columns called groups. Rows represent elements in order of increasing atomic numbers. Columns represent elements with similar properties

7. Understanding the periodic table As you go across a period from left to right how does the type of element change? Elements go from being metals, to metalloids, to nonmetals. What happens to the number of protons in the nucleus of an atom? It increases. As you go from top to bottom in a group, what happens to the atomic mass? To the atomic number? The atomic mass increases. The atomic number also increases by either 8 or 18.