definition :
A table in which the chemical elements are arranged in order of increasing atomic number
The Periodic Table is like a map of all the chemical elements in the universe. Each element has a unique number called the atomic number, which tells how many protons are in its atom.
The elements are arranged in rows, called periods, and columns, called groups or families.
Elements in the same group act similarly in chemical reactions because they have the same number of outer electrons.
As you move from left to right across a period, elements go from being metals to nonmetals.
Metals are on the left and center. They are shiny, conduct heat, and are bendable.
Nonmetals are on the right. They don’t conduct electricity well and are often gases or brittle solids.
In between metals and nonmetals are metalloids, which have mixed properties.
Some special columns have names:
Group 1: Alkali metals – very reactive (like sodium).
Group 17: Halogens – also very reactive (like chlorine).
Group 18: Noble gases – not reactive at all (like helium and neon).
The bottom part of the table (the two rows below) includes rare earth elements called lanthanides and actinides.
notes
periodic table is made up of columns and rows
there are the groups in it Alkali metals ,Halogens ,Noble gases
There are 118 elements in the periodic table.
How does the periodic table reflect the electronic structure of atoms?
What trends can you observe in atomic radius, ionization energy, and electronegativity across periods and groups?
Why are noble gases chemically inert, and how does their position explain this?
How do the properties of elements change as you move down a group or across a period?
Why do alkali metals react so vigorously with water compared to alkaline earth metals?
How do transition metals differ from main group elements in their chemical behavior and bonding?
What makes the lanthanides and actinides unique in the periodic table?
keywords
Periods
Atomic number
Atomic mass
Electron configuration
Alkali metals
Alkaline earth metals
Transition metals
Lanthanides
Actinides
Noble gases
Halogens
Metalloids
Reactivity trends
Ionization energy
Electronegativity
Atomic radius
Valence electrons
Periodicity
Electron shells (s, p, d, f blocks)
Mendeleev
New elements (superheavy elements)
Your note is too short.
What does the atomic number of an element represent?
What are the rows in the periodic table called?
What are the columns in the periodic table called?
Why do elements in the same group behave similarly in chemical reactions?
What happens to the type of elements as you move from left to right across a period?
Where are metals located on the periodic table?
List two properties of metals.
Where are nonmetals found on the periodic table?
What are metalloids, and where are they found on the periodic table?
Which group is known as alkali metals?
Name a very reactive element from Group 1.