which element has the same number of valence electrons as bromine?
A. krypton
B. selenium
C. potassium
D. Chlorine
why are sodium and potassium in the same group on the periodic table?
A. they have similar atomic wieghts
B. they are both hard and brittle
C. they have similar reactivity
D. they are both colorless
gases at room temperature
To determine which element has the same number of valence electrons as bromine, we need to look at the periodic table. Let's count the valence electrons for each option:
A. Krypton is a noble gas located in Group 18 (Group 8A) of the periodic table. It has 8 valence electrons.
B. Selenium is located in Group 16 (Group 6A) of the periodic table. It has 6 valence electrons.
C. Potassium is located in Group 1 (Group 1A) of the periodic table. It has 1 valence electron.
D. Chlorine is located in Group 17 (Group 7A) of the periodic table. It has 7 valence electrons.
Comparing these options to bromine (Br), which is located in Group 17 (Group 7A), we can see that chlorine (Cl) also has 7 valence electrons. Therefore, the answer is D. Chlorine.
Now let's move on to the second question about sodium and potassium being in the same group on the periodic table.
A. Sodium and potassium do not have the same atomic weights. Sodium (Na) has an atomic weight of 22.99 g/mol, while potassium (K) has an atomic weight of 39.10 g/mol.
B. Sodium and potassium are not both hard and brittle. Sodium is a soft metal that can be easily cut with a knife, while potassium is even softer and can be easily cut with a piece of string.
C. The correct answer is C. Sodium and potassium are in the same group on the periodic table because they have similar reactivity. Both elements are highly reactive metals that readily lose their single valence electron to form positive ions.
D. Sodium and potassium are not both colorless. Sodium has a distinct yellow color, especially when it reacts with substances such as water.
Therefore, the answer to the second question is C. They are in the same group because they have similar reactivity.
The element that has the same number of valence electrons as bromine is D. Chlorine.
The reason why sodium and potassium are in the same group on the periodic table is C. they have similar reactivity.