Chapter U1.12, Problem 1TAI

Interpretation Introduction

Interpretation:

The difference between the atoms of one element from those of another element is to be described.

Concept introduction:

In 1803 a scientist called Dalton gave an atomic theory to describe the structure of an atom. The atomic theory states that all matter is made of atoms. Since Dalton’s time many scientists have created different models to describe atoms and sub - atomic particles. An atom has a nucleus made of protons and neutrons, with electrons revolving around the nucleus.

Answer to Problem 1TAI

Atoms of one element are different from those of another element in the number of protons present in the nucleus of atoms or their atomic number.

Explanation of Solution

The nucleus is in the center of the atom and electrons are outside the nucleus. In a neutral atom, protons are positively charged and electrons are negatively charged.

Mendeleev arranged the elements on a periodic table in order of their increasing atomic mass. Moseley later discovered that atoms of each element differ by one proton from the atoms of the element before it on the periodic table.

The number of protons in the nucleus of an element is called atomic number. In a neutral atom, the atomic number is also equal to the number of electrons because the overall charge in an atom is 0, so the number of protons is equal to the number of electrons.

Therefore, we can say that the atoms of one element differ from atoms of other elements in their atomic number.

Conclusion

An atom is made of particles called electrons, protons and neutrons. Atoms of one element are different from atoms of other elements. The number of protons in each element is unique.