Atomic Theory All matter consists of atoms All the atoms of one element are identical in mass & other properties & are different from atoms of any other element Atoms of one element cannot be converted into atoms of another element Compounds are the chemical combination of two or more chemicals in a specific ratio

Periodic Table Atomic number: number of protons, ultimate organizer of periodic table Mass number: sum of number of protons and neutrons Isotopes: Number of protons & # of electrons in a given element are always the same but neutrons may vary Atoms of same element with different # of neutrons are called isotopes For an element, not an ion, #protons = #electrons

Which of the following represents isotopes of the same element Which of the following represents isotopes of the same element? Which element?

Periodic Table Columns are called groups, elements within groups share similar chemical reactivities & properties Rows are called periods Elements with A after them (on top) are called main group elements Elements with B after them (on top) are called transition elements

Periodic Properties Demo Play demo All these metals display similar properties, i.e. react with H2O to form H2 + metalOH React in an increasingly vigorous manner Reaction: Metal + H2O  Metal Hydroxide + H2 Lithium Reaction: Write the reaction for Na or K

In your notebook, fill this in Atom # of Protons # of Neutrons # of Electrons Mass # 10 11 Barium 82 21 24 15 16

Arrangement of subatomic particles in atom

Characteristics of the 3 basic subatomic particles