Döbereiner grouped the known elements into <em>triads</em> (sets of three) so that
• The <em>atomic mass of the middle element</em> was approximately the average of the other two
• The <em>chemical properties of the middle element</em> were between those of the other two
• The <em>physical properties of the middle element</em> were between those of the other two
One example of a triad is Li – Na – K.
(a) Atomic mass of Na = 23.0 u
Average atomic mass of Li and K = (6.9 u + 39.1 u)/2 = 46.0 u/2 = 23.0 u
(b) Li reacts slowly with water. Na reacts rapidly. Potassium reacts violently.
(c) Melting point of Na = 371 °C.
Average melting point of Li and K = (454 °C + 330 °C)/2 = 784 °C/2
= 392 °C
Answer:
8.3028894e-22
Explanation:
5x10^2 atoms/1 x 1 mol/6.022x10^23
Answer:
5
Explanation:
just subtract 20-25 and 5 is left over which is how much the water when up with the rock.
15 is the group that phosphorus is found in.
Answer:
1 strong acid
2 yes they are dangerous
Explanation:
Since nearly all of it is dissociated in water, it is called a strong acid.
2 yes Concentrated strong acids can cause severe and painful burns. The pain is due in part to the formation of a protein layer, which resists further penetration of the acid
