Question

Two representative elements are in the same period of the periodic table. Which statement correctly describes the atoms of the two elements?(1 point)
They have the same number of valence electrons.
They have the same number of valence electrons.

They have valence electrons in different energy levels.
They have valence electrons in different energy levels.

They have valence electrons in the same energy level.
They have valence electrons in the same energy level.

They have the same number of electrons.Helium is in group 18 of the periodic table. How is helium different from the other elements in this group?(1 point)Helium atoms have valence electrons in the first energy level, while atoms of the other elements in the group have valence electrons in the second energy level.
Helium atoms have valence electrons in the first energy level, while atoms of the other elements in the group have valence electrons in the second energy level.

Helium atoms have 2 valence electrons, while atoms of the other elements in the group all have 8 valence electrons.
Helium atoms have 2 valence electrons, while atoms of the other elements in the group all have 8 valence electrons.

Helium atoms have a full outer energy level, while atoms of the other elements in the group do not have a full outer energy level.
Helium atoms have a full outer energy level, while atoms of the other elements in the group do not have a full outer energy level.

Helium atoms have 2 electrons, while atoms of the other elements in the group all have 18 electrons.
Use the periodic table to answer the question.
Which element has atoms with valence electrons in a higher energy level than those of calcium (Ca)?
lithium (Li)
lithium (Li)

cesium (Cs)


bromine (Br)

oxygen (O)
Use the periodic table to answer the question.
Which statement best describes the arrangement of electrons in an atom of fluorine (F)?
There are seven electrons in the first energy level and two electrons in the second energy level.
There are seven electrons in the first energy level and two electrons in the second energy level.

There are five electrons in the first energy level and two electrons in the second energy level.
There are five electrons in the first energy level and two electrons in the second energy level.

There are two electrons in the first energy level and seven electrons in the second energy level.
There are two electrons in the first energy level and seven electrons in the second energy level.

There are two electrons in the first energy level and five electrons in the second energy level.

Answer 1

Elements in the periodic table are arranged in the increasing order of their atomic number.

An atom will contain equal amount of protons and electrons. If two elements are in same period of periodic table then these elements will have same number of electrons.

Helium is one of the seven elements which are called as noble gases. This gas is odorless, tasteless and colorless which makes it unique from other elements.

It has two valence electrons while atoms of other elements in the group have 8 valence electrons.

Lithium has one valence electron, while calcium atom has 2 valence electrons.

The highest level of energy is due valence electrons of an atom.  The correct answer is Lithium.

Fluorine element has 9 electrons. There are 2 electrons in the first energy level and seven electrons in the second energy level.

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