There are many things but mainly they are
-hardness (metal or nonmetal)
-reactivity
-their charge
Elements in the first two columns and in the last six are called representative elements. All of the elements in one of these columns have the same number of valence electrons or electrons in the outermost energy level. The transition metals don't have such order these are the elements in the middle of the table.
Elements in the same rows have the same number of electron shells.
the elements in a column have similar characteristics. for example: the noble gas family is a family because they all barely react with ANY ELEMENT and are therefore classified together.
how do the propertiess of elements in the same row of the peoridic table compare
They have the same number of valence (outermost) electrons. This makes them also have similar reactivity characteristics.
the noble gases
http://en.wikipedia.org/wiki/Periodic_tablegroups or families are verticalA period is a horizontal row in the periodic table. Although groups are the most common way of classifying elements, there are some regions of the periodic table where the horizontal trends and similarities in properties are more significant than vertical group trends.
Elements in a vertical group (Group 1, Group 2, etc.) of the periodic share in common the same number of valence electrons. The valence electrons are the electrons in the outer shell of an atom, and their number has a lot to do with their chemistry.
The columns of the periodic table are called groups (or families). All elements in a group have the same number of electrons in their outer orbital. Furthermore, since many chemical properties are determined by the location of the outermost electrons, elements in the same group will share many common properties.
Iron on the periodic table
litium, and elements in the 2nd period (row) are pretty common
valency..
valency..
periodic table
The elements in the same vertical columns, also called groups or families, all share common traits with each other (for example, all of the alkali metals react violently when placed in water.) This is because all of the elements in one group contain the same number of valence electrons.
The number of electrons in the outter shell
The horizontal lines are called "periods" and show how many "shells" each atom hasThe horizontal rows in the periodic table are called periods. The vertical columns are called groups.
http://en.wikipedia.org/wiki/Periodic_tablegroups or families are verticalA period is a horizontal row in the periodic table. Although groups are the most common way of classifying elements, there are some regions of the periodic table where the horizontal trends and similarities in properties are more significant than vertical group trends.
Elements in a vertical group (Group 1, Group 2, etc.) of the periodic share in common the same number of valence electrons. The valence electrons are the electrons in the outer shell of an atom, and their number has a lot to do with their chemistry.
In space, the most common elements are?
NOTHIN !
The periodic table contain all chemical elements, placed in a rational order.
They are .......... .......... .......... .......... .......... ..........