+1 only for all elements (except for hydrogen)
hydrogen can have +1 and -1 as their oxidation numbers.
Group 1 elements have an oxidation number of +1.
Group 1 elements have an oxidation number of +1, group 2 elements have an oxidation number of +2, group 17 elements have an oxidation number of -1, and group 18 elements (noble gases) have zero oxidation number since they are chemically unreactive.
Elements that have a single oxidation number include group 1 elements (e.g. sodium, potassium) which have an oxidation number of +1, and group 2 elements (e.g. magnesium, calcium) which have an oxidation number of +2.
Hydrogen has -1 and +1 oxidation numbers. Other elements have +1 only
Elements with fixed oxidation numbers include alkali metals (group 1 elements) which have a +1 oxidation state, alkaline earth metals (group 2 elements) which have a +2 oxidation state, and nonmetals in group 17 (halogens) which have a -1 oxidation state in compounds.
Group 1 elements have an oxidation number of +1.
Group 1 elements have an oxidation number of +1, group 2 elements have an oxidation number of +2, group 17 elements have an oxidation number of -1, and group 18 elements (noble gases) have zero oxidation number since they are chemically unreactive.
Elements that have a single oxidation number include group 1 elements (e.g. sodium, potassium) which have an oxidation number of +1, and group 2 elements (e.g. magnesium, calcium) which have an oxidation number of +2.
Hydrogen has -1 and +1 oxidation numbers. Other elements have +1 only
Elements with fixed oxidation numbers include alkali metals (group 1 elements) which have a +1 oxidation state, alkaline earth metals (group 2 elements) which have a +2 oxidation state, and nonmetals in group 17 (halogens) which have a -1 oxidation state in compounds.
The oxidation number for K in KCl is +1, as alkali metals (Group 1 elements) typically have a +1 oxidation state. For Cl in KCl, the oxidation number is -1, as halogens (Group 17 elements) typically have a -1 oxidation state when they form ionic compounds.
The oxidation numbers for elements in Group 1A (alkali metals) are typically +1. For elements in Group 2A (alkaline earth metals), the oxidation number is typically +2.
The maximum oxidation number is theoretically equal to the number of valence electrons. For example the oxidation number of chlorine among different compounds can vary from -1 to +7. An exception for this is fluorine, which only have -1 and 0 as its oxidation numbers.
The oxidation number of Na in NaH is +1. In general, group 1 elements like sodium (Na) have an oxidation number of +1 in most compounds.
The oxidation numbers for the first 20 elements in the periodic table are typically as follows: Group 1 elements: +1; Group 2 elements: +2; Group 13 elements: +3; Group 14 elements: +4 or -4; Group 15 elements: -3; Group 16 elements: -2; Group 17 elements: -1; Group 18 elements: 0. Keep in mind that oxidation numbers can vary in different compounds and contexts.
Because they have one valence electrons, and if they lose this electron they attain an oxidation number of +1
Group 1 elements are the most electropositive in nature and have only 1 valence electron. So, they always show the oxidation state of +1.