The question is incomplete but i will try to offer as much help as i can.
Answer:
See explanation
Explanation:
The electron was discovered by J.J Thompson. His model of the atom was called the plum-pudding model of the atom.
He discovered that cathode rays being negatively charged particles were deflected by a magnet in just the same way as moving, negative electrically charged particles.
Similarly, in an electric field, they are deflected towards the positive plate of the electrostatic field which shows that they are negatively charged.
Antoine Henri Becquerel discovered radioactivity when he was studying
X- rays.
He had been studying phosphorescent uranium ores and hypothesized that they might absorb sunlight and reemit it as X-rays.
His hypothesis was wrong, but his experiments led to the discovery of <em>natural radioactivity</em>.
a) 1 mole of Ne
b) i/2 mole of Mg
c) 1570 moles of Pb.
d) 2.18125*10^-13 moles of oxygen.
Explanation:
The number of moles calculated by Avogadro's number in 6.23*10^23 of Neon.
6.23*10^23= 1/ 6.23*10^23
= 1 mole
The number of moles calculated by Avogadro's number in 3.01*10^23 of Mg
3.2*10^23=1/6.23*10^23
= 1/2 moles of Pb.
Number of moles in 3.25*10^5 gm of lead.
atomic weight of Pb=
n=weight/atomic weight
= 3.25*10^5/ 207
= 1570 moles of Pb.
Number of moles 4.50 x 10-12 g O
number of moles= 4.50*10^-12/16
= 2.18125*10^-13 moles of oxygen.
Answer:
78.85
Explanation:
To <u>calculate the average atomic mass of the isotopes </u>we use the <em>given masses and abundances</em>, as follows:
- Mass of Isotope 1 * Abundance of Isotope 1 + Mass of Isotope 2 * Abundance of Isotope 2 + ....
In other words:
- 78 amu * 75/100 + 81 amu * 15/100 + 82 amu * 10/100 = 78.85
So the answer is 78.85.
Magnesium (Mg) has atomic number 12 with electronic configuration :
The valence shell of Mg is 3s which has 2 electrons as shown in above electronic configuration.
Therefore, A = 3 and B =2
