The Periodic Table Matter can be defined as anything that takes up space, has mass, and has inertia. Chemistry is the study of matter and its interactions. This is an introduction to the most basic categories of matter.

Beginning of the Periodic Table Dmitri Mendeleev Discovered pattern of the elements Arranged by increasing atomic mass Periodic-occurs in regular intervals Dmitri Mendeleev was the first person to discover the pattern among elements. He decided to arrange them by different properties including density, appearance, melting point. Then he arranged them in order of increasing atomic mass. This showed a pattern. The elements that had similar properties fit this pattern Periodic-occurs in regular intervals

Henry Moseley Rearranged elements by increasing atomic number Periodic Law-chemical and physical properties of elements change periodically with the atomic numbers of the elements Medeleev’s periodic table had some elements missing and the order was not consistent so Mosley found a way to arrange them so they are. Periodic Law basically means that chemical and physical properties of an element depend on their atomic number Periodic Law-chemical and physical properties of elements change periodically with the atomic numbers of the elements

The Periodic Table 115 elements 3 classes of elements Metals Nonmetals Metalloids Amount of electrons in the outermost level helps determine class The electrons in the outermost level is what separates all of these classes apart. Metals have few electrons in their outermost level. Nonmetals have an almost complete set of electrons in their outermost level. Metalloids have around half of a complete set.

Metals Key Properties Found to the left of the zig-zag Shiny Malleable (bendable) Ductile Good conductors of electricity and thermal energy Solid at room temperature (except Hg) Found to the left of the zig-zag -most elements are metals Hg=Mercury

Nonmetals Key Properties (opposite of metals) Not malleable or ductile Not shiny Poor conductors of thermal energy and electricity Found to the right of the zig-zag -almost complete set of e- in outer ring Halogens (gr 18) have complete set of e- in outer level,

Metalloids Semiconductors Border the zig-zag Have some properties of metals and some of nonmetals Border the zig-zag Semiconductors- -border zig zag -7 metalloids- B, Si, Ge, As, Sb, Te, Po -half of a complete set of electrons in outer level -some props of both metals and nonmetals

Reading the Periodic Table Each square has: Element’s Name Chemical Symbol Atomic Number Atomic Mass

Period Def-a horizontal row of elements Elements in the same period have the same number of electron shells

Group Def- a vertical column of elements Share the same chemical and physical properties Called a family a vertical column of elements-share the same chemical properties and physical (called family)

Group 1: Alkali Metals Most reactive metals Properties: So reactive they are only found as compounds Properties: Soft Color (silver) Shiny Low density Ex: NaCl – Sodium Chloride (table salt) Group 1: Alkali Metals -most reactive metals. So reactive in nature they are only found as a compound -sodium chloride-table salt -share softness, color (silver), shininess, low density

Group 2: Alkaline-Earth Metals Less reactive than Group 1 Properties Color (silver) Higher density than alkali metals Mixed with other elements to make things Airplanes (Mg) or cement and chalk (Ca) Group 2: Alkaline-Earth Metals Alkaline-Earth Metals are mixed with other elements to make things we use. Magnesium is mixed w/ other low density elements to make airplanes. Calcium is also mixed to make cement or chalk

Groups 3-12: Transition Metals Properties: Shiny Good conductors of thermal energy and electricity Higher density and melting point than Groups 1 &2 Less reactive than Groups 1 &2 Groups 3-12: Transition Metals

Lanthanides and Actinides Two rows on the bottom the periodic table Part of Transition metals group Lanthanides  Top row Actinides  Bottom row Lanthanides and Actinides Lanthanides=shiny, reactive metals -used to make steel

Group 13: Boron Group Properties: Ex: Aluminum Solid at room temperature Reactive Ex: Aluminum Most common and most abundant Group 13: Boron Group -Earth Metals -aluminum is most common and most abundant  how can aluminum be used in so many things? When aluminum reacts w/ oxygen a layer of aluminum oxide quickly forms which prevents further reaction

Group 14: Carbon Group Properties: Solid at room temperature Carbon makes up proteins, fats, and carbohydrates Essential for life Group 14: Carbon Group Most of these elements are found in daily life either as the pure element or as a compound

Group 15: Nitrogen group Nitrogen makes up 80% of the air we breathe Solid at room temperature Group 15: Nitrogen group -solid at room temp (except N) -N makes up 80% of air Elements in this group can form compounds. Nitrogen forms a compound with hydrogen to become ammonia.

Group 16: Oxygen Group Oxygen makes up 20% of the air we breathe All elements in this group, except for Oxygen, are solid at room temperature Group 16: Oxygen Group -all but O are solid @ room temp -O makes up 20% of air

Group 17: Halogens Properties: Poor conductors of electricity Violent reactions w/ alkali metals Combine with most elements to form salts Chemical properties are similar but physical properties very different Group 17: Halogens -poor conductors of electric current, violent reactions w/ alkali metals to form salts, never in uncombined form in nature -halogens-combine w/ most elements to form salts ex: NaCl -chemical props similar but physical props very diff

Group 18: Noble Gases Unreactive gases Ex: Helium, Neon Neon Lights -noble gases-unreactive gases (nonmetals)

Hydrogen In a group of its own Properties: Colorless Odorless Gas (at room temperature) Low density Explosive reaction with Oxygen Most abundant element in the universe Hydrogen -colorless, odorless gas @ room temp, low density, explosive reaction w/ oxygen -in a group of its own -most abundant element in the universe