No, atoms of different elements can have different sizes and weights. The size and weight of an atom are determined by several factors, including the number of protons, neutrons, and electrons it contains.
The atomic size, or atomic radius, refers to the distance from the nucleus of an atom to its outermost electron. The atomic size can vary across the periodic table. Generally, as you move from left to right across a period, the atomic size tends to decrease because the increasing number of protons in the nucleus exerts a stronger pull on the electrons, causing them to be closer to the nucleus. Similarly, as you move down a group, the atomic size tends to increase because new electron shells are added, increasing the distance between the nucleus and the outermost electrons.
The atomic weight, or atomic mass, of an atom is the combined mass of its protons, neutrons, and electrons. Atomic masses are measured relative to a standard unit called the atomic mass unit (amu), where 1 amu is approximately equal to the mass of a proton or a neutron. The atomic weight of an element is usually given as an average value since different isotopes of the same element can have different mass numbers. The atomic weight takes into account the abundance of each isotope and their respective masses.
So, the size and weight of an atom can vary depending on the element and its isotopes. Atoms of different elements can have different atomic sizes and atomic weights due to variations in the number of protons, neutrons, and electrons they possess.