There are many things but mainly they are
-hardness (metal or nonmetal)
-reactivity
-their charge
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.
The columns on a periodic table are called "groups" or "families." Groupings are based on the number of valence electrons elements within the same group have in common, which influences their chemical properties.
The alkali and alkaline earth and transitions are all groups of the periodic table ANOTHER POINT OF VIEW: A group or family is the vertical columns on The Periodic Table of the Elements.
A family or group of elements in chemistry refers to a set of elements classified together based on their similar properties and chemical behaviors. Elements in the same group often share common characteristics such as valence electron configuration and reactivity patterns. Examples include the alkali metals group (Group 1) and the halogens group (Group 17) on the periodic table.
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.
valency..
valency..
The periodic table of elements is the table that arranges different elements based on their common properties in rows and columns. It helps to organize and classify elements by their atomic number, electron configuration, and chemical properties.
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 horizontal rows are named 'PERIODS'. The vertical columns are named '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.
The columns in the periodic table, also known as groups, are organized based on the number of electrons in the outermost energy level of the elements. Elements in the same column have similar chemical properties due to their similar electron configurations. The columns are numbered from 1 to 18, with the elements in the same column sharing common characteristics.
The columns on a periodic table are called "groups" or "families." Groupings are based on the number of valence electrons elements within the same group have in common, which influences their chemical properties.
The alkali and alkaline earth and transitions are all groups of the periodic table ANOTHER POINT OF VIEW: A group or family is the vertical columns on The Periodic Table of the Elements.
A family or group of elements in chemistry refers to a set of elements classified together based on their similar properties and chemical behaviors. Elements in the same group often share common characteristics such as valence electron configuration and reactivity patterns. Examples include the alkali metals group (Group 1) and the halogens group (Group 17) on the periodic table.
They indicate groups of elements which often (but not always) share common properties. (cf. http://en.wikipedia.org/wiki/Periodic_table#Groups)One of the common characteristics in a group is that they share the same number of electrons on the outer shell.
Elements in the same group of the periodic table have similar chemical properties due to having the same number of valence electrons. This leads to similar reactivity and bonding behavior within a group of elements.