Note: You will find ionisation energy covered in detail in another part of this site. If you don't get into the habit of thinking about all the possible factors, you are going to make mistakes.įirst ionisation energy is the energy needed to remove the most loosely held electron from each of one mole of gaseous atoms to make one mole of singly charged gaseous ions - in other words, for 1 mole of this process: That isn't true if you try to compare atoms from different parts of the Periodic Table. If you are talking about atoms in the same Group, the net pull from the centre will always be the same - and you could ignore it without creating problems. It is a matter of setting up good habits. Why, then, bother about exploring the net pull on the electrons from the centre of the atom? Note: You may think that this is all a bit long-winded! It is, after all, fairly obvious that atoms will get bigger if you add more layers of electrons. That means that the atoms are bound to get bigger as you go down the Group. Obviously, the more layers of electrons you have, the more space they will take up - electrons repel each other. The only factor which is going to affect the size of the atom is therefore the number of layers of inner electrons which have to be fitted in around the atom. Work it out for calcium if you aren't convinced. This is equally true for all the other atoms in Group 2. The positive charge on the nucleus is cut down by the negativeness of the inner electrons. In each case, the two outer electrons feel a net pull of 2+ from the nucleus. Use the BACK button on your browser to return quickly to this page. Note: If you aren't sure about writing electronic structures using s and p notation it might be a good idea to follow this link before you go on. The pull the outer electrons feel from the nucleus. The number of layers of electrons around the nucleus Notice that beryllium has a particularly small atom compared with the rest of the Group. You can see that the atomic radius increases as you go down the Group. If you choose to follow this link, use the BACK button on your browser to return quickly to this page. Note: You will find atomic radius covered in detail in another part of this site. The physical properties are extremely difficult to explain, however. The same ideas tend to recur throughout the atomic properties, and you may find that earlier explanations help to you understand later ones. You will find separate sections below covering the trends in atomic radius, first ionisation energy, electronegativity and physical properties.Įven if you aren't currently interested in all these things, it would probably pay you to read most of this page. This page explores the trends in some atomic and physical properties of the Group 2 elements - beryllium, magnesium, calcium, strontium and barium. Atomic and physical properties of Periodic Table Group 2ĪTOMIC AND PHYSICAL PROPERTIES OF THE GROUP 2 ELEMENTS
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