The Modern Periodic Table

The Current Periodic Table Mendeleev wasn’t too far off. Now the elements are put in rows by increasing ATOMIC NUMBER!! The horizontal rows are called periods and are labeled from 1 to 7. The vertical columns are called groups are labeled from IA to VIIIA

Groups… Here’s Where the Periodic Table Gets Useful!! Elements in the same group have similar chemical and physical properties!! (Mendeleev did that on purpose.) Why?? They have the same number of valence electrons. They will form the same kinds of ions.

Families on the Periodic Table Columns are also grouped into families. Families may be one column, or several columns put together. Families have names rather than numbers. (Just like your family has a common last name.)

Mendeleev The periodic table arranges all the elements in groups according to their properties. Horizontal rows are called PERIODS Vertical columns are called GROUPS

HHe LiBeBCNOFNe NaMgAlSiPSClAr KCaFeNiCuZnBrKr AgIXe PtAuHg Fact 1: Elements in the same group have the same number of electrons in the outer shell (this correspond to their group number) E.g. all group 1 metals have __ electron in their outer shell These elements have __ electrons in their outer shell These elements have __ electrons in their outer shells

HHe LiBeBCNOFNe NaMgAlSiPSClAr KCaFeNiCuZnBrKr AgIXe PtAuHg Fact 2: As you move down through the periods an extra electron shell is added: E.g. Lithium has 3 electron in the configuration 2,1 Potassium has 19 electrons in the configuration __,__,__,__ Sodium has 11 electrons in the configuration 2,8,1

HHe LiBeBCNOFNe NaMgAlSiPSClAr KCaFeNiCuZnBrKr AgIXe PtAuHg The Periodic Table Fact 3: Most of the elements are metals: These elements are metals This line divides metals from non- metals These elements are non-metals

HHe LiBeBCNOFNe NaMgAlSiPSClAr KCaFeNiCuZnBrKr AgIXe PtAuHg The Periodic Table Fact 4: (Most important) All of the elements in the same group have similar PROPERTIES. This is how I thought of the periodic table in the first place. This is called PERIODICITY. E.g. consider the group 1 metals. They all: 1)Are soft 2)Can be easily cut with a knife 3)React with water

–Each period ends with a completely filled outer shell that has the maximum number of electrons for that shell. –The number identifying the A families identifies the number of electrons in the outer shell, except helium –The outer shell electrons are responsible for chemical reactions. –Group A elements are called representative elements –Group B elements are called transition elements. Families on the Periodic Table

Chemical “Families” –IA are called alkali metals because the react with water to from an alkaline solution –Group IIA are called the alkali earth metals because they are reactive, but not as reactive as Group IA. They are also soft metals like Earth. –Group VIIA are the halogens These need only one electron to fill their outer shell They are very reactive. –Group VIIIA are the noble gases as they have completely filled outer shells They are almost non reactive.

Four chemical families of the periodic table: the alkali metals (IA), the alkaline earth metals (IIA), halogens (VII), and the noble gases (VIIIA).

Hydrogen Hydrogen belongs to a family of its own. Hydrogen is a diatomic, reactive gas. Hydrogen was involved in the explosion of the Hindenberg. Hydrogen is promising as an alternative fuel source for automobiles

Alkali Metals 1 st column on the periodic table (Group IA) not including hydrogen. Very reactive metals, always combined with something else in nature (like in salt). Soft enough to cut with a butter knife

Alkaline Earth Metals Second column on the periodic table. (Group IIA) Reactive metals that are always combined with nonmetals in nature. Several of these elements are important mineral nutrients (such as Mg and Ca

Transition Metals Elements in groups IIIB-IIB Less reactive harder metals Includes metals used in jewelry and construction. Metals used “as metal.”

Boron Family Elements in group IIIA Aluminum metal was once rare and expensive, not a “disposable metal.”

Carbon Family Elements in group IVA Contains elements important to life and computers. Carbon is the basis for an entire branch of chemistry. Silicon and Germanium are important semiconductors.

Nitrogen Family Elements in group VA Nitrogen makes up over ¾ of the atmosphere. Nitrogen and phosphorus are both important in living things. Most of the world’s nitrogen is not available to living things. The red stuff on the tip of matches is phosphorus.

Oxygen Family or Chalcogens Elements in group VIA Oxygen is necessary for respiration. Many things that stink, contain sulfur (rotten eggs, garlic, skunks,etc.)

Halogens Elements in group VIIA Very reactive, volatile, diatomic, nonmetals Always found combined with other element in nature. Used as disinfectants and to strengthen teeth.

The Noble Gases

Elements in group VIIIA VERY unreactive, monatomic gases Used in lighted “neon” signs Used in blimps to fix the Hindenberg problem. Have a full valence shell.