1. (1)K-2e- (2)L-8e- (3)M-7e-
=> 2+8+7 = 17 => Z=17
2. Ba = bariu ; Cu = cupru ; Mg = magneziu ; Hg = mercur (hidrargium) ; Ca = calciu ; C = carbon ; N = azot (nitrogen) ; P = fosfor ; N = sodiu (natrium) ; Ne = neon
3. (1)K-2e- (2)L-6e- => Z=8 => 8p+ ; 8e- si 8n0
a. (1)K-2e- (2)L-6e-
b. Z=8
c. 8p+
d. A = Z + n0 = 8+8 = 16 u.a.m.
4. M.H2 = 2x1 = 2 g/mol
=> 1 mol H2 ............ 2 g H .............. 2x6,022x10la23 atomi H
40 g H .............. n = 2,41x10la25 atomi H
5. M.S = 32 g/mol
n = nr.moli = m/M = 6,4/32 = 0,2 moli S
6.
₆¹²C = 6p+ => n0 = A-Z = 12-6 = 6
₆¹³C = 6p+ => n0 = A-Z = 13-6 = 7
₆¹4C = 6p+ => n0 = A-Z = 14-6 = 8
7.
5Cl
V
10Ar
4K
7Si
8.
n = m/M => M = m/n = 120/3 = 40 g/mol
=> elementul este Ca cu A = 40
