What happens to the number of valence electrons in atoms of elements as we go down a group of the periodic table?
The number of valence electrons remains the same as we go down a group.
Concept: Study of Specific Groups in Periodic Table
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There are a few things to look out though when trying to figure out the number of valence electrons.
Group 1 elements have one valence electrons, and Group 2 elements have 2 valence electrons. Groups 13-17 have 3,4,5,6 & 7 valence electrons respectively. The noble gases (group 18) have 8 valence electrons except for He which has only 2 valence electrons.
Elements in groups 3-12 are referred to as the transition metals and there are more exceptions to rules for determining valence electrons for these elements.
Here is a video review of Lewis structures and valence electrons.
Hope this helps!
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Question | Answer | ||||||||||||||||||||
1. When elements are arranged in order of increasing atomic number, there is a repeating pattern of their chemical and physical properties. | Periodic Law | ||||||||||||||||||||
2. What happens to the number of valence electrons as you go down a group? | Number of valence electrons stays the same. | 3. What happens to the number of valence electrons as you go across a period? | Number of valence electrons increases. | 4. The tendency of an atom to attract electrons to form an ionic bond. | Electronegativity | 5. The size of an atom | Atomic radius | 6. Energy required to remove an electron from a neutral atom. | Ionization energy | 7. The trend in ionization energy and electronegativity as you go down a group and why this occurs. | Decreases as you go down a group because electrons are close to the nucleus in smaller atoms making the attraction stronger. | 8. The trend in ionization energy and electronegativity as you go across a period and why this occurs. | Increases to the right because electrons are held more tightly because of an increased charge. | 9. The trend in atomic radius as you go down a group and why this occurs. | Increases as you go down a group because higher energy levels have larger orbitals so the size of atom increases. | 10. The most reactive nonmetal. | Fluorine | 11. The trend in atomic radius as you go across a period and why this occurs. | Increases to the left because electrons are held more loosely. | 12. The most reactive metal. | Francium |
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