Answer:
the properties of three undiscovered elements is the correct answer.
Explanation:
After he completed his work Mendeleev predicted the properties of the undiscovered elements.
In the year 1871, Dmitri Mendeleev predicted the detailed existence and the properties of the three elements that are undiscovered and he gained tremendous fame.
He left the gap in the table to put the elements which are not identified at that time and by glancing at the physical and chemical properties of an element next to the gap, Mendeleev could predict the properties of the not discovered elements.
Hey there,
Question : <span>The average, year-after-year conditions of temperature, precipitation, winds, and cloud in an area are known as its?
Answer : A, climate
Hope this helps :))
<em>~Top♥</em>
</span>
4.6 x 10 to the -1 power.
Explanation:
Y has 13 protons and we know that Aluminium (Al) too has 13 protons.
So , element Y = Aluminium
• In an element , no. of protons = no. of electrons. So , Y has 13 electrons.
• Mass no. of Y (Aluminium) = 27.
• Also we know that ,
Mass number = no. of protons + no. of neutrons
So,
No. of neutrons = 27 - 13 = 14
• Valence electrons are the electrons which are present in the outermost shell of an element.
Electronic Configuration of Y = 2,8,3
So, Y has 3 valence electrons.
• We know that Y is Aluminium & Aluminium is a metal. So , Y is a metal.
• Valency of Y = +3