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Which of the following Group 7A elements is the most reactive?

Cl (chlorine)

I (iodine)

F (fluorine)

Br (bromine)


Which of the following gases emit colors when an electric current is applied?

hydrogen and helium

argon and krypton

fluorine and chlorine

oxygen and nitrogen

Verified Answer :

Question 1

Fluorine is the most reactive element in group 7A of elements.


Further Explanation

Reactivity of Non-metals down the group

  • The reactivity of non-metals decreases down the group in a periodic table.
  • This is because as you move down the group the number of energy levels increases which reduces the nuclear charge and thus reducing the ease of gaining electrons.

Group 7A elements

  • Group 7A elements are also called halogens. Halogens are non-metals in group 7A in the periodic table.
  • Group 7A contain seven electrons in their outermost energy level and therefore requires one electron to attain a stable configuration.
  • Reactivity of halogens like other metals decreases down the group, therefore fluorine is the most reactive in the group with iodine being the least reactive.
  • This is because fluorine has few energy levels compared to other elements in the group and thus has high nuclear charge which makes it easier for an atom of fluorine to gain electrons.


Question 2  

Argon and Krypton gases emit colors when an electric current is applied  


Further Explanation

  • Argon and krypton are examples of noble gases. Noble gases are elements in group 8 of the periodic table.  
  • Noble gases such as Argon, neon and krypton are used in lamps such as gas-discharge lamps, as they produce light by sending an electric discharge through an ionized gas known as plasma.
  • Each of these gas used emit a particular wavelengths based on its atomic structure, its emission spectrum, which determines the color of the light from the lamp.
  • Argon for example gives off a violet to pale lavender blue color, while Krypton emits a gray off-white to green and at high peak currents emits a bright blue-white color.



Keywords: Reactivity, Chemical families, group 7A of elements


Learn more about:

  • Group 7A of elements: https://brainly.com/question/1593421
  • Reactivity of non-metals: https://brainly.com/question/1593421
  • Noble gases: https://brainly.com/question/12722854


Level: High school

Subject; Chemistry

Topic: Chemical families and the periodic table


lublana

Answer:

1.Fluorine (F)

2.Argon and Krypton

Explanation:

1.Group 7A elements: it is that group of periodic table in which each element has 7 electrons in outermost shell.

The outermost shell can be filled by maximum 8 electrons.Therefore, the elements of this group require 1 electron to full fill their outermost shell.

Fluorine is the most electronegative element because the size of fluorine is small.

The electronegativity of an element is the ability to attract the electrons towards itself.

The reactivity means gain or loose electrons.

The fluorine has high electronegativity therefore, it is most reactive non-metal.

Answer;Fluorine(F)

2.Argon and Krypton are noble gases because their outermost shell is fully filled.They  emit colors when an electric current is applied because when current passes through it then electron are excited  by absorbing energy and they jump from ground state to higher energy level.

When they return from higher to lower energy level  then they release absorbed energy in the form of color light.

Hence,they emit colors.

Answer:Argon and Krypton

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