VIIA
Group 1 elements have very low electronegativies and group 7 elements have very high electronegativities, so that both are reactive with almost every other element, the group 1 elements by donating electrons and the group 7 elements by accepting electrons.
In comparison with ionic bonds, the difference in electronegativities of elements in a covalent bond have a lower difference in electronegativities. A covalent bond occurs between two nonmetals that have a difference in electronegativities that is 1.7 or less. Usually an ionic bond has a difference in electronegativities that is greater than 1.7, but not always.
Group 1 and group 2 elements are reactive metals and react readily with water. They also react readily at high temperatures with oxygen. Over the millenia any free deposits would react to form compounds.
It is because the group 1 and 7 elements have a high reactivity. The reactivity is far too high to use on there own because the elements in these groups react with air and/or water.
Group 8 (noble gases) have the highest first ionization energy because they are already stable and don't want to lose any electrons. Ignoring the noble gases, however, group 7 halogens (F, Cl, Br, I, etc.) have the highest first ionization energy. That's because these elements have seven valence electrons, and they don't want to give up any electrons - they want another one!
Group 1 elements have very low electronegativies and group 7 elements have very high electronegativities, so that both are reactive with almost every other element, the group 1 elements by donating electrons and the group 7 elements by accepting electrons.
In comparison with ionic bonds, the difference in electronegativities of elements in a covalent bond have a lower difference in electronegativities. A covalent bond occurs between two nonmetals that have a difference in electronegativities that is 1.7 or less. Usually an ionic bond has a difference in electronegativities that is greater than 1.7, but not always.
Group 1 and group 2 elements are reactive metals and react readily with water. They also react readily at high temperatures with oxygen. Over the millenia any free deposits would react to form compounds.
It is because the group 1 and 7 elements have a high reactivity. The reactivity is far too high to use on there own because the elements in these groups react with air and/or water.
These elements are highly unstable because of for group1- IP is low and for group 7 electron affinity is high
Group 8 (noble gases) have the highest first ionization energy because they are already stable and don't want to lose any electrons. Ignoring the noble gases, however, group 7 halogens (F, Cl, Br, I, etc.) have the highest first ionization energy. That's because these elements have seven valence electrons, and they don't want to give up any electrons - they want another one!
Elements such as helium and neon are noble gases and ave a full set of 8 electrons in their outer shell. this means they wont form covalent bonds. they also have high electronegativities so they wont react with acids or form ionic compounds.
Because the electronegativities values of Be and Mg are high in comparission of other elements of the group. These two metals form poler covalent bond with hydrogen and due to polarity the units of these hydrides are linked to gather in the form of chain by hydrogen bond. so thier hydrides are called polymeric hydrides.
polar
Electronegativity of an atom determines how it will share the electrons in a covalent bond. If an atom has a high electronegativity and it is bonded to an atom with a low one, the shared electrons will stay closer to the one with higher electronegativity. This molecule will be polar. If two atoms are bonded with similar electronegativities, the electrons will be shared evenly and it will be nonpolar. Nonpolar bonds are uncommon because there are many atoms with different electonegativities, so the chance that they are very close is low. Basically kid, if you are using Holt Rinehart and Winston chapter test/quiz for covalent compounds, the answer is A) one atom usually attracts electrons more strongly than the other (varying electronegativities) YAY!!
(apex!) the electronegativities of the two atoms are NOT equal.
A polar covalent bond.