Answer:
B. Periods
Explanation:
The horizontal rows in the periodic table are periods.
on the picture below, u can see an example
Explanation:
question 44
the number 35 of bromine represents the atomic number
question 45
29 protons,
27 electrons
29-27 = +2
the charge on the following particle is
+2
Answer:
answer-
The relative atomic mass = 204.4
explanation:
Thallium -203 = 30%
Thallium -205 = 70%
Therefore ,
relative mass of thallium = (30×203 + 70×205)/100
relative mass of thallium = (20440)/100
relative mass of thallium = 204.40 amu
Thus,
relative atomic mass of thalium =204.4 ( to 1 decimal place)
Answer is: the discovery of sub atomic particles like electrons.
J. J. Thomson discovered the electron in 1897.
His "plum pudding" model (1904) suggested: the electrons are embedded in the positive charge.
With this model, he abandoned his earlier hypothesis (the atom was composed of immaterial vortices).
J.J. Thomson placed two oppositely charged electric plates around the cathode ray. He did experiments using different metals as electrode materials and found that the properties of the cathode ray remained constant no matter what cathode material he used.
Tomson concluded that atoms are divisible and that the corpuscles are their building blocks (atoms are made up of smaller particles).