The groups on the periodic table are arranged by valence electron number. (Ex. Group 2 has 2 valence electrons in the electron configuration
Answer:
<u>»</u><u> </u><u>Similarities</u><u> </u><u>:</u>
☑ They both react by chemical means, to produce either an element or compound as the end product of the chemical reaction.
• Take an example of Magnesium reacting with cold water:

• If it reacts with steam:

• [ Element: <em>Magnesium</em><em> </em>and Compound: <em>Water</em><em> </em>]
They are both classified under atomic substances cause they are made up of microscopic molecules known as atoms.
☑ They are both formed up by microscopic substances known as atoms.
<u>»</u><u> </u><u>Differences</u><u> </u><u>:</u>
☑ Compounds generally have higher molecular masses than elements.
☑ Compounds are formed through bonding by elements while elements can naturally exist or formed by extraction, purification and concentration
<h2>Example of Physical change </h2>
Ice forming and then melting back into water are an example of physical change because the nature of water is liquid. Yet when it freezes then it becomes into solid form. The water which is liquid then freezes to form ice form which is as a solid which is also a physical change.
If we see that when ice which is frozen and in solid form starts to melt by heat then it converts into water which is liquid form. This indicates that water freezes to form ice means liquid to solid therefore its shape changes which is a physical change. When ice melts it becomes solid to liquid it also changes shape and subsequently takes a physical change.
Ernest Rutherford discovered the electron cloud.
Answer:
atoms of different elements combine and form new elements