Lab: physical and chemical changes
assignment: lab report active

Explanation:

Physical Change:                                                                                            

The changes that occur only due to change in shape or form but their chemical or internal composition remain unchanged.

These changes were reversible.

They have same chemical property.

These changes can be observed with naked eye.

Example :

Water converting to Ice

Water converting to gas

In this water molecule remain the same only they rearrange themselves that change its state of mater not composition

Chemical changes:

The changes, that occur due to change in the composition of a substance and result in a different compound is known as chemical change.

These changes are irreversible

These changes occur due to chemical reactions

These may not be observed with naked eye

Example:

Combustion of fuel or wood: that oil or wood convert into energy, CO₂ and ash in case of wood

Boiling of egg: that change the chemical composition of protein in the egg

The reaction of Hydrogen and oxygen:

H₂ (g)  + O₂  (g) > 2H₂O  (l)

alkaline metals are lithium, sodium, rubidium, potassium, cesium and francium.

alkali metals have electronegativity from 0.7 to 1, lowest in periodic table of elements, which means that alkali metals (i group in periodic table) has positive oxidation number in compounds.

electronegativity is a chemical property that describes the tendency of an atom to attract a shared pair of electrons towards itself.

alkaline metals (far left in main group) have lowest ionizations energy and easy remove valence electrons,

for example, potassium is the alkali metal and has a single valence electron in the outer electron shell.

electron configuration of potassium is: ₁₉k 1s²2s²2p⁶3s²3p⁶4s¹.

they can not exist alone in nature, because they are very reactive.

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