Answer:
168.812 g/mol
Explanation:
atomic mass. of Be= 9.012
atomic mass of Br= 79.90
because there is a 2 after Br you double the atomic mass
79.90(2)= 159.8
To find the molar mass add the atomic masses of each element
9.012+159.8=168.812
The answer is: <span>The principal idea here is how r they obtained:
for example: sodium u put equal molar concentrations of sodium (Na) and sodium ion (Na+) together in a beaker , then dip in this solution a platinium wire (zero potential) which is connected to a normal hydrogen electrode (electrode with zero potential) then u see the reading of the whole circuit
if it is negtive, this means negative potential which means that the reducing property predominates where Na(reducing agent) is oxidized and electrons r accumulated on the platinum which gives it negative charge
This means that (Na) is a reducing agent, its strength depends on the value of the potential obtained, and here the table can help you
If u want to know if it's strong red. agent, look for it in the table, see if it has higher reduction potentail (or lower oxidation potential, same idea) than most other substances then it is reducing agent
and vice versa
So if we look at ur examples, u will find that MnO4- is the very strong oxidizing agent (has highest oxidation potential) (lowest reduction potential)
H+ and H2 are both with zero potential, no redox properties
And lastly Na and Na+:
This u can know from ur knowledge in chemistry, that sodium is very rarely found in elemental form and always in the form of ion so u can deduce that Na is the very strong reducing agent
or u can see the value of its standard oxi or red potetial and deduce which is the predominating form of them.
I hope this helps</span>
Valence electrons is an outer shell electron that is associated with an atom, and that can participate in the formation of a chemical bond if the outer shell is not closed. In a single covalent bond, both atoms in the bond contribute one valence electron in order to form a shared pair.
The presence of valence electrons can determine the elements chemical properties, such as its valence—whether it may bond with other elements and, if so, how readily and with how many. In this way, a given element's reactivity is highly dependent upon its electronic configuration. For a main group element, a valence electron can exist only in the outermost electron shell; in a transition metal, a valence electron can also be in an inner shell.
An atom with a closed shell of valence electrons (corresponding to an electron configuration s2p6 for main group elements) tends to be chemically inert. Atoms with one or two valence electrons more than a closed shell are highly reactive due to the relatively low energy to remove the extra valence electrons to form a positive ion. An atom with one or two electrons less than a closed shell is reactive due to its tendency either to gain the missing valence electrons and form a negative ion, or else to share valence electrons and form a covalent bond.
Similar to a core electron, a valence electron has the ability to absorb or release energy in the form of a photon. An energy gain can trigger the electron to move (jump) to an outer shell; this is known as atomic excitation. Or the electron can even break free from its associated atom's shell; this is ionization to form a positive ion. When an electron loses energy (thereby causing a photon to be emitted), then it can move to an inner shell which is not fully occupied.
When forming ions, elements typically gain or lose the minimum number of electrons necessary to achieve a full octet. For example, fluorine has seven valence electrons, so it is most likely to gain one electron to form an ion with a 1- charge.
Answer:
C or D
Explanation:
Hope it helped a little bit
Answer: A
Explanation it gets all mushy THATS a physical change
