What Property Of Elements Generally Decreases Across A Period?A. Electronegativity B. Atomic Radius C. Atomic Number D. Reactivity

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What Property of Elements Generally Decreases Across a Period?

Understanding the Periodic Table

The periodic table is a tabular arrangement of the chemical elements, organized by their atomic number (number of protons in the nucleus), electron configuration, and recurring chemical properties. The elements are listed in order of increasing atomic number (number of protons in the nucleus) and are grouped into rows called periods and columns called groups or families.

Properties of Elements Across a Period

As we move across a period from left to right, the atomic number of the elements increases by one. This increase in atomic number results in a decrease in the size of the atoms, which is known as the atomic radius. The atomic radius is the distance from the nucleus of an atom to the outermost electron in a neutral atom.

Atomic Radius

The atomic radius is a measure of the size of an atom. It is defined as the distance from the nucleus of an atom to the outermost electron in a neutral atom. The atomic radius decreases across a period because the number of protons in the nucleus increases, which results in a stronger attraction between the nucleus and the electrons. This stronger attraction pulls the electrons closer to the nucleus, resulting in a decrease in the atomic radius.

Electronegativity

Electronegativity is the ability of an atom to attract electrons in a covalent bond. It is a measure of the tendency of an atom to attract electrons towards itself. Electronegativity increases across a period because the number of protons in the nucleus increases, which results in a stronger attraction between the nucleus and the electrons. This stronger attraction makes it more difficult for the atom to share electrons with other atoms, resulting in an increase in electronegativity.

Atomic Number

The atomic number is the number of protons in the nucleus of an atom. It is a unique identifier for each element and is used to distinguish one element from another. The atomic number increases across a period because each element has one more proton in its nucleus than the previous element.

Reactivity

Reactivity is the ability of an atom to participate in chemical reactions. It is a measure of the tendency of an atom to form bonds with other atoms. Reactivity decreases across a period because the number of protons in the nucleus increases, which results in a stronger attraction between the nucleus and the electrons. This stronger attraction makes it more difficult for the atom to form bonds with other atoms, resulting in a decrease in reactivity.

Conclusion

In conclusion, the property of elements that generally decreases across a period is the atomic radius. The atomic radius decreases because the number of protons in the nucleus increases, resulting in a stronger attraction between the nucleus and the electrons. This stronger attraction pulls the electrons closer to the nucleus, resulting in a decrease in the atomic radius.

Key Takeaways

  • The atomic radius decreases across a period because the number of protons in the nucleus increases.
  • The atomic radius is a measure of the size of an atom.
  • Electronegativity increases across a period because the number of protons in the nucleus increases.
  • The atomic number increases across a period because each element has one more proton in its nucleus than the previous element.
  • Reactivity decreases across a period because the number of protons in the nucleus increases.

Frequently Asked Questions

  • What is the atomic radius?
  • Why does the atomic radius decrease across a period?
  • What is electronegativity?
  • Why does electronegativity increase across a period?
  • What is the atomic number?
  • Why does the atomic number increase across a period?
  • What is reactivity?
  • Why does reactivity decrease across a period?

References

  • Petrucci, R. H., Harwood, W. S., & Herring, F. G. (2007). General chemistry: Principles and modern applications. Pearson Prentice Hall.
  • Atkins, P. W., & De Paula, J. (2006). Physical chemistry. Oxford University Press.
  • Brown, T. E., & LeMay, H. E. (2008). Chemistry: The central science. Pearson Prentice Hall.

Glossary

  • Atomic radius: The distance from the nucleus of an atom to the outermost electron in a neutral atom.
  • Electronegativity: The ability of an atom to attract electrons in a covalent bond.
  • Atomic number: The number of protons in the nucleus of an atom.
  • Reactivity: The ability of an atom to participate in chemical reactions.