Presentation on theme: "Section 1: Introduction to Atoms"— Presentation transcript:
1 Section 1: Introduction to Atoms How did atomic theory develop and change?What is the modern model of the atom?
2 How is the periodic table organized? Imagine you have a piece ofaluminum foil, and you cut itin half. If each of these pieces iscut in half a second, third, andfourth time, the pieces becomesmaller but are still aluminum.How small must a piece be sothat at the next cut it will nolonger be aluminum?
3 Atomic Theory and Models Dalton thought that atoms were like smooth, hard spheres that could not be broken into smaller pieces.
4 Modern Model of an AtomThis model of a carbon atom consists of positively charged protons and neutral neutrons in a nucleus that is surrounded by a cloud of negatively charged electrons.
5 Modern Model of an AtomThis model of an atom shows electrons in a frozen position that can be used to learn about chemistry.The nucleus contains protons and neutrons that make up the mass of the atom.The tiny electrons are arranged in different energy levels around the nucleus.5
6 Particles in an AtomAn atom is composed of positively charged protons, neutral neutrons, and negatively charged electrons. Protons and neutrons are about equal in mass. An electron has about 1/2,000 the mass of a proton or neutron.
7 Identifies the name of the element Atomic Number# protonsTop # in Periodic TableIdentifies the name of the elementExample:# protons (+) = 6Atomic # = 6Element Name:Carbon7
8 Isotopes & Mass NumberIsotopes are atoms with the same number of protons and electrons but differerent number of neutrons.Mass number = total particles in the nucleus (protons + neutrons)