As you go across the period of the periodic table, you are increasing the atomic number while decreasing the atomic radius, but what causes this trend?
you increase the atomic number but i don't know why
I think because the atoms gain more electrons the higher they go on the periodic table
Generally, the atoms are increasing atomic number meaning that they are increasing the number of protons in the nucleus. Therefore, the positive charge in the nucleus is increasing but the electrons that are being added are in the same outer shell; therefore, the outer electrons feel an increasing pull by the nucleus and the result is a smaller atom.
More protons are gained(represnted by increasing atomic number) across the periodic table. As this happens, the electrons are pulled tighter into the nucleus since the positive protons in the nucleus attract the negative electrons. This causes the atomic radius to decrease because it is denser since electrons were pulled in.
The trend of increasing atomic number and decreasing atomic radius as you go across a period of the periodic table is primarily influenced by two factors: effective nuclear charge and electron shielding.
Effective nuclear charge refers to the attraction between the positively charged nucleus and the negatively charged electrons in the outermost energy level. As you move across a period, the number of protons in the nucleus increases, resulting in a greater positive charge in the nucleus. However, the number of electrons in the outermost energy level remains the same for elements in the same period. As a result, the increasing nuclear charge pulls the electrons closer to the nucleus, causing the atomic radius to decrease.
Electron shielding refers to the repulsion between electrons in the inner energy levels and those in the outer energy level. As you move across a period, the number of inner electrons remains constant, while the number of protons in the nucleus increases. The additional protons exert a stronger pull on the outermost electrons, resulting in a smaller atomic radius. This increased effective nuclear charge overcomes the electron shielding effect.
In summary, the trend of increasing atomic number and decreasing atomic radius across a period of the periodic table is primarily due to the increasing effective nuclear charge and the constant number of inner electrons, which cause the outermost electrons to be pulled in closer to the nucleus.