Periodic Table of Elements Matter: Properties and Changes
Warm up Instructions: 1. Use the periodic table of elements to looks for the letters in your first or last name to write your name in elements. 2. Draw a square for each element your are going to use. 3. Write the element symbol in the center, add the atomic number in the top right, and write the name of the element below the element symbol. 4. If the letter isn t in the periodic table just write the letter.
Review Elements: one of the basic substances that combine to form all other substances cannot be broken down into simpler substances by ordinary chemical means Scientists have discovered about 118 elements. Atoms: is the smallest particles of an element that has all the properties of that element Each element is made up of atoms that differ from those of every other element.
History about Elements In 1869, a total of 63 elements had been discovered. Dmitri Mendeleev discovered a set of pattern in the properties of the elements. Example: Silver and copper are both shiny metals that tarnish if exposed to air. He noticed that a pattern of properties appeared when he arranged the elements in order of increasing atomic mass. Atomic mass is the average mass of all the isotopes of that elements is equal to the total mass of protons, neutrons, and electrons in the atom
Mendeleev s Periodic Table In 1869, Mendeleev published the first periodic table. In this periodic table, the properties of the elements repeat in each period, or row, of the table. He left three blank spaces in the table. He predict that this spaces would be filled by elements that had not yet been discovered and even predicted the properties of those elements.
Modern Periodic Table After protons were discovered, elements were rearranged according to atomic number. Some elements changed positions and the patterns of properties became more regular. The modern periodic table contains over 100 squares, one of each element. The periodic table is a chart that organizes information about the elements. Each square includes the element s atomic number, chemical symbol, name, and atomic mass.
Finding Data on Elements Each element has a square that include: atomic number chemical symbol name atomic mass
Finding Data on Elements Atomic number is the number of protons in the nucleus of an atom. Chemical symbol for an element usually consists of one or two letters. (iron - Fe) Average atomic mass (weight) is an average because most elements consist of a mixture of isotopes. Isotopes are atoms with the same number of protons and a different number of neutrons.
Organization of the Periodic Table The properties of an element can be predicted from its location in the periodic table. Each horizontal row of the table is called a period. As you move across a period from left to right, the properties of elements change in a predictable pattern. There are seven periods of elements. (Left side - highly reactive metal, right side - unreactive gas)
Organization of the Periodic Table The elements in a column are called a group, or family. The group are numbered from Group 1 on the left to Group 18 on the right. The family name of a group is typically the name of the first element in the column. Elements in each group have similar characteristics. (metals react violently with water are in one group)
Review - Classwork 1. In what order did Mendeleev arrange the elements in the first periodic table? 2. What pattern did Mendeleev discover when he arranged the elements? 3. Describe two differences between Mendeleev s periodic table and the modern periodic table? 4. List three kinds of information about an element that can be found in a square of the periodic table? 5. What element has 47 protons in its nucleus? 6. Why aren t the atomic masses of most elements whole numbers? 7. What does an element s location in the periodic table tell you about that element?