Work it out for potassium if you aren't convinced.

This is equally true for all the other atoms in Group 1. The positive charge on the nucleus is cut down by the negativeness of the inner electrons. In each case, the outer electron feels a net pull of 1+ from the nucleus. Use the BACK button on your browser to return quickly to this page. Note: If you aren't sure about writing electronic structures using s and p notation it might be a good idea to follow this link before you go on. The pull the outer electrons feel from the nucleus. The number of layers of electrons around the nucleus You can see that the atomic radius increases as you go down the Group. If you choose to follow this link, use the BACK button on your browser to return quickly to this page. Note: You will find atomic radius covered in detail in another part of this site. The same ideas tend to recur throughout the atomic properties, and you may find that earlier explanations help to you understand later ones. You will find separate sections below covering the trends in atomic radius, first ionisation energy, electronegativity, melting and boiling points, and density.Д®ven if you aren't currently interested in all these things, it would probably pay you to read the whole page. This page explores the trends in some atomic and physical properties of the Group 1 elements - lithium, sodium, potassium, rubidium and caesium. More information can be found at this web site: periodic Just click on the elements.Atomic and physical properties of Periodic Table Group 1ДЄTOMIC AND PHYSICAL PROPERTIES OF THE GROUP 1 ELEMENTS In fact, natural potassium has three isotopes with 20, 21 and 22 neutrons with the abundance of 93.26 %, 0.01 % and 6.73 % respectively. This tells you that there must be some other isotopes for potassium. If you read the atomic weight for potassium it reads 39.098. (The atomic number for oxygen is 8, and the atomic mass is 15.9994). Oxygen, with atomic number of 8, for example, can have 8, 9, or 10 neutrons. The same element may contain varying numbers of neutrons elements that have the same number of protons but different numbers of neurons are called isotopes. Things can be a bit more complicated however. Since we know that the number of protons is 19 we can calculate the number of neutrons (39 19) as 20. This means that the atomic weight is 39 for both protons and neutrons. It is the number under the element symbol. This can also be found in the periodic table. To find out the number of neutrons you have to look at the atomic mass or weight of the element. This tells you that potassium has 19 protons and - since the number of protons is the same as the number of electrons- also 19 electrons. So if you look for potassium (symbol K in the periodic table), you will find that it has the atomic number of 19. Now, the atomic number is also the number of protons in an element. Hydrogen is the first element with an atomic number of 1. In this table the elements are listed according to their atomic number. How can you find out how many protons (= electrons) an element has? You look at the periodic table. The number of protons and electrons is the same in a neutral (uncharged) atom. Protons have a positive (+) charge, neutrons have no charge -they are neutral. A proton has an atomic mass of 1 u (unified atomic mass). The atomic mass for protons and neutrons is the same. Protons and neutrons are responsible for most of the atomic mass.

What are the numbers of atoms for potassium?ДЄs you may know, atoms are composed of three different types of particles: protons, neutrons, which are found in the nucleus, and electrons which are found in the electron cloud around the nucleus.

Potassium atom