because a periodic table shows the arrangement of element according to their atomic number and their valence neither
isotopes nor colour
We can predict the number of valence electrons by which group of the Periodic table an element resides.
For example Lithium is in group 1 and has 1 valency electron.
Option (b) is the correct answer.
Valence electrons is the number of electrons present in the outermost shell of an atom.
So, when we move across a period from left to right then there will be increase in number of valence electrons.
For example, valence electrons in carbon is 4, nitrogen has 5 valence electrons, oxygen has 6 valence electrons.
Thus, we can conclude that number of valence electrons increases for elements change across a period.
A: Elements in the same group share the same number of valence electrons.
D: Elements in the same group share the same reactive properties.
A periodic group is simply the arrangement of elements vertically on the periodic table.
There are about 8 main groups of elements on the periodic table.Elements in the same group have the same number of valence electrons. This is usually observed in their group numbers. Due to this, they all share the same chemical properties which makes them react the same way. Usually, the number of atoms shell increases down the group. Across a period, elements share the same number of orbitals in their structure. No two elements on the periodic table shares the same number of total electrons.
B. By the group number of the A columns
Valence electrons which is a term that describes the number of electrons in the highest occupied energy level for an element helps to categories the elements into groups.
Hence, based on Chemical Abstracts Service, CAS grouping, it is shown or concluded that the periodic table indicate the number of valence electrons an element has by the group number of the A columns
The maximum number of electrons that can occupy the outermost energy level or valence shell of a Representative Element is eight (the exception is helium, which also exhibits a filled valence shell, but only it requires only 2 electrons).
I think C
Incorrect Answers to Review:
20. In the periodic table, the period number indicates
A. the number of the outermost energy level for elements in that period.
B. the number of valence electrons for elements in that period.
C. the number of dots shown on the Lewis dot diagrams for elements in that period.
D. the reactivity levels for elements in that period.
You answered : B
Found in : Section 1.3
Increases by an unit.
The periodic table refers to the table in which the chemical elements are arrangement in the increasing order of their atomic number (Z). This table contains 18 vertical columns, known as groups and 7 horizontal rows, called columns.
As we move across the period, i.e. left to right from one column to another; the number of valence electrons in the valence shell of a chemical element progressively increases by an unit.
mass = 6.75 g
volume = 9 cm³
d = mass / volume
d = 6.75 / 9
d = 0.7 g/cm³
a) an elements color