1. ELEMENTS AND THE PERIODIC TABLE
CHAPTER 15
ELEMENTS AND THE PERIODIC TABLE

2. ORGANIZING ELEMENTS Dmitri Mendeleev
Looked at similar physical and chemical properties
Atomic mass: the average mass of one atom of the element
Bonding power: the number of chemical bonds an element can form

3. FIRST PERIODIC TABLE
Mendeleev noticed patterns when elements were arranged in order of increasing atomic mass
Periodic table, the properties of the elements repeat in each row

4. ATOM INSIDE OUTSIDE NUCLEUS: THE CORE OF THE ATOM
PROTONS: POSITIVE CHARGE
NEUTRONS: NEUTRAL CHARGE
OUTSIDE
ELECTRON CLOUD OR ELECTRON ORBIT
ELECTRONS: NEGATIVE CHARGE

5. ATOM ATOMIC MASS UNIT: USED TO MEASURE THE PARTICLES OF AN ATOM
AMU
ATOMIC NUMBER: THE NUMBER OF PROTONS IN THE NUCLEUS
UNIQUE FOR EACH ELEMENT
AN ATOM HAS A NEUTRAL CHARGE

6. READING THE PERIODIC TABLE
AN ELEMENT’S PROPERTIES CAN BE PREDICTED FROM ITS LOCATION IN THE PERIODIC TABLE
GROUPS: THE VERTICAL COLUMNS 18
ALSO KNOWN AS FAMILIES
PERIODS: THE HORIZONTAL ROWS
7 PERIODS

7. Fe INSIDE THE SQUARE IRON 26 55.847 ATOMIC NUMBER ELEMENT SYMBOL
ELEMENT NAME
55.847
ATOMIC MASS

8. VALENCE ELECTRONS
THE ELECTRONS THAT ARE INVOLVED IN TRANSFER OR SHARING IN THE CHEMICAL BONDS
THE ELEMENTS IN EACH GROUP OF THE PERIODIC TABLE HAVE THE SAME NUMBER AND ARRANGEMENT OF VALENCE ELECTRONS

9. 8 5 1 3 6 2 7 4
2 –
2 - 3