The illustrations in this section show the differences between macroscopic particles and atom-sized particles. Section 1 describes Young's Double Slit Experiment, which showed that atom-sized particles exhibit wave-like properties by producing wave-like interference patterns. This allows us to convert between moles and mass. We can also relate this atomic mass to the mass in g of a mole of the substance. For example, one atom of hydrogen is 1.01 amu. This is the mass of a single atom of the element in a mass unit specifically for atoms. When we see the average atomic masses written on the periodic table, they are in atomic mass units (amu or u). We can now look at the atomic masses on the periodic table in a new light. We can use Avogadro's number to convert between the number of atoms and the number of moles of a substance. The number 6.022 × 10 23 is known as Avogadro's Number. A dozen always equals 12, no matter what the object is.Ī mole (often abbreviated as mol) always equals 6.022 × 10 23 objects. The mole is a counting number in the same way a dozen is a counting number. We use moles as a counting number to keep track of these enormous numbers of atoms we encounter in the lab and in our lives. Even small objects in our macroscopic everyday world consist of an enormous number of atoms. In chemistry, we need a way to connect the microscopic world of atoms to the macroscopic world we live in. Try the practice problems to do these types of calculations yourself. This section describes how to determine the average atomic mass of an element if we know the isotope masses and their relative abundance. Then read the section "Isotopic Mixtures and Abundances" near the bottom of the page. When we see the mass of an element on the periodic table, we are seeing the weighted average of the masses of all isotopes of that element. Read this section, which explains how we write atomic symbols with atomic numbers and mass numbers. We can write this as A = Z + N where A is mass number, Z is atomic number, and N is number of neutrons. For a given isotope, we define the mass number, A, as the atomic number plus the number of protons. However, the number of neutrons can vary within atoms of a given element.Ītoms of the same element with different numbers of neutrons are called isotopes. For a neutral atom (not a charged ion), the number of electrons must equal the number of protons. We define the atomic number, Z, as the number of protons in an atom. As stated above, we define the elements by their number of protons.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |