Organization of The Periodic Table

Nucleus Center of the atom. Makes majority of the atom’s mass. Made of Protons and Neutrons. Nucleus

Protons Part of the nucleus Have positive (+) charge

Neutrons Part of the nucleus Have neutral charge

Electrons Orbit around the nucleus Have negative (-) charge

Atomic Number Definition: the number of protons in the nucleus Tells us the identity of the element. Every element is defined by the number of protons in its nucleus

Isotopes Atoms with the same number of protons but different numbers on neutrons Example: Carbon So you can change the number of neutrons and the element still maintains its identity

Questions 1) What particles make up an atom? 2) What are the charges on these particles? 3) What particles make up the nucleus?

Questions 1) What is Oxygen’s atomic number? 2) How many protons does Oxygen have? 3) If I have 4 protons what element am I? 4) If I have 4 neutrons what element am I?

Reading the Periodic Table Mass

Atomic Mass Definition: the ~ mass of one atom of an element Tells us how much one atom weighs in atomic mass units. Mass

Organization of The Periodic Table Group/Family Period Ordered by atomic mass. Columns arranged to form groups with similar properties

Assessment Which element has the greatest atomic mass? Lithium Sodium Potassium Rubidium Rubidium

Reactivity The ease and speed with which an element combines, or reacts, with other elements or compounds Pure sodium reacts explosively with air

Groups/families of elements have similar reactivity Group 1: metals that react violently with water Group 18: Gases that barely react at all

Atoms have neutral charge # of Protons (+) = # of Electrons (-) = 0 charge Example: Hydrogen How many electrons does C have? carbon has 6 electrons.

Take home message The properties of an element can be predicted from its location on the Periodic Table

Metals, Metalloids, and Nonmetals

Metals Shiny Solids (at room temp) Malleable – can be hammered flat Ductile – can be pulled into wire High Conductivity – ability to transfer heat or electricity to another object

Reactivity of Metals Low High Metals will usually lose electrons when they react with other elements

Nonmetals Sulfur Opposite of properties of metals Not shiny Poor conductors Mostly gases (at room temperature) Solids are brittle Sulfur

Reactivity of Nonmetals Low Low High Nonmetals will usually gain or share electrons when they react with other elements

Some Important Nonmetals Carbon – important element for making up living organisms Noble Gases – group 18 – very nonreactive. Have full outer shells.

Metalloids Inbetween metals and nonmetals Solids (at room temp) brittle and hard Semiconductors – can conduct electricity under some conditions but not others. very important for computer chips Most common example – Silicon – in sand and glass

Assessment The atomic number is the number of valence electrons. neutrons. protons in the nucleus. electrons in the nucleus. Protons in nucleus

Assessment The periodic table is a chart of the elements that shows the repeating pattern of their energies. properties. element symbols. names. properties

Assessment Which piece of information cannot be found in a square on the periodic table? Atomic mass. Chemical symbol. Atomic number. Number of neutrons. Number of neutrons

Assessment Which side of the periodic table contains most of the nonmetals? Left side. Right side. Middle. Magnesium.

Assessment Which is not a property of nonmetals? Brittle. Nonmalleable. High conductivity. Most are gases at room temperature Magnesium.