The Atom =Uy0m7jnyv6U

III. Subatomic Particles A. Atomic Number B. Mass Number and Isotopes C. Electrons and Ions D. Nuclear and Hyphenation Notation E. Average Atomic Mass IV. Weighing and Counting Atoms A. Mole Atoms B. Mole Mass C. Mass Atoms

Electron Proton Neutron NameSymbolCharge Relative mass Actual mass (g) e-e- p+p+ n0n amu 9.11 x x III.Subatomic Particles A. Comparing Particles 1amu

1. Atomic number 1. the number of protons in the nucleus of an atom a. identifies the element a. identifies the element b. no two elements have the same atomic number b. no two elements have the same atomic number 2.Ex. C is 6, N is 7 and O is 8 carbon nitrogen oxygen carbon nitrogen oxygen III.Subatomic Particles B. Atomic Number and Mass Number

2. Mass number a. the number of protons plus neutrons in the nucleus of an atom b. mass number is very close to the mass of an atom in amu (atomic mass units) c. two atoms with the same atomic number but different mass number are called isotopes 1) (mass #) – (atomic #) = #n 0 1) (mass #) – (atomic #) = #n 0 III.Subatomic Particles B. Atomic Number and Mass Number

1.Nuclear Notation is one method for depicting isotopes of an element 2.contains the symbol of the element, the mass number, and the atomic number III.Subatomic Particles C. Nuclear Notation X Mass number Atomic number

How many protons? How many protons? How many neutrons? How many neutrons? How many electrons? How many electrons? III.Subatomic Particles C. Nuclear Notation Na 23 11

1. Element symbol or name – mass # 2. EXAMPLES a. Fluorine-19 a. Fluorine-19 b. C-14 b. C-14 c. U-238 c. U-238 III.Subatomic Particles C. Hyphen Notation

1. Electrons and Ions a. For neutral atoms, #e - = #p + a. For neutral atoms, #e - = #p + b. If there are more electrons, a negative ion b. If there are more electrons, a negative ion forms (anion) forms (anion) c. If there are less electrons, a positive ion c. If there are less electrons, a positive ion forms (cation) forms (cation) 3IM 3IM For now, we will work only with neutral atoms III.Subatomic Particles D. Ions

The modern table Elements are still grouped by properties. Elements are still grouped by properties. Similar properties are in the same column. Similar properties are in the same column. Order is in increasing atomic number. Order is in increasing atomic number. Added a column of elements Mendeleev didn’t know about. Added a column of elements Mendeleev didn’t know about. The noble gases weren’t found because they didn’t react with anything. The noble gases weren’t found because they didn’t react with anything.

Horizontal rows are called periods Horizontal rows are called periods There are 7 periods There are 7 periods Represent the # of Represent the # of Electron levels Electron levels

1A 2A3A4A5A6A 7A 8A 0 The elements in the A groups are called the representative elements The elements in the A groups are called the representative elements

The group B are called the transition elements u These are called the inner transition elements and they belong here

Group 1A are the alkali metals Group 1A are the alkali metals Group 2A are the alkaline earth metals Group 2A are the alkaline earth metals

Group 7A or 17 is called the Halogens Group 7A or 17 is called the Halogens Group 8A or 18 are the noble gases Group 8A or 18 are the noble gases