Aim: How to distinguish an atom in the ground state and the excited state? DO NOW: Identify Green = proton Blue= neutron Red= electron Which element is this? How can we tell? How many electrons are in the first shell? Second shell?

Atomic Orbitals An atomic orbital is thought of as the most probable location of an electon Each shell in an atom is subdivided into orbitals. Electrons are found in the orbitals. )1 )2 )3)4 nucleus

Electrons and Electron Shells(Energy Levels) When electrons are arranged in an atom, the innermost shell is filled first and then the outer shells are filled Each shell can hold a certain amount of electrons The number of electrons in a shell cannot surpass the shell’s capacity Energy Level/Shell Total Electrons per Level 1 2 8 3 18 4 32

Electron Configuration Electron configuration is a condensed way of representing the pattern of electrons in an atom. For oxygen: 2-6 (2 electrons in first shell, 6 in second shell)

Electronic Structure Element Bohr Structure Electron Configuration Electrons Periodic Table Group Fluorine (F) 2-7 2 e- in 1st shell 7 e- in 2nd shell 17 Neon (Ne) 2-8 2e- in 1st shell 8 e- in 2nd shell 18 Sodium (Na) 2-8-1 1 e- in 3rd shell 1 Calcium (Ca) 2-8-8-2 8 e- in 3rd shell 2 e- in 4th shell 2

Ground State An atom in the ground state is defined as electrons being in the lowest energy electron configuration The electron configuration as written in the periodic stable shows the electrons in their ground state

Energy and Electrons Electrons further away from the nucleus have more energy than electrons closer to nucleus Ex: For the aluminum atom, the two electrons in the first shell have less energy than the 3 electrons in the 3rd shell Discussion: Electrons can move throughout the electrons cloud from one shell to another shell. In terms of electrons absorbing or releasing energy, how do you think an electron in the 2nd shell can jump to the 3rd shell?

Excited State Electrons can move to a higher energy level (shell) without filling the lower energy level first electrons do this by absorbing energy An excited state is an energy state of higher energy Excited electrons fall back to the ground state by releasing energy in the form of light Energy released are small, specific amounts of energy

Note When atom becomes excited, the electrons jump to a higher energy level; HOWEVER, the OVERALL number of electrons does not change

Explain in terms of electrons and energy how an atom can go from ground to excited state Excited to ground state

Draw Bohr Diagram for Aluminum atom in the Ground State and the Excited State On the arrows, write if energy is absorbed or released by the atom

Sample Questions Examples Fluorine. How many protons? Electrons? Ground state e- config (Periodic Table) 2-7 Working with your partner write 2 possible excited state e- configs 1-7-1 2-6-1 1-8 Note how an inner level is left partially filled b/c an e- has jumped to a higher energy level Note that TOTAL # OF e- REMAINS THE SAME! 

Regent Questions The Bohr model of the atom was developed in the early part of the twentieth century. A diagram of the Bohr model for one atom, in the ground state, of a specific element is shown below. The nucleus of this atom contains 4 protons and 5 neutrons State the atomic number and the mass number of this element. State the number of electrons in each shell in this atom in the ground state. Using the Bohr model, describe the changes in electron energy and electron location when an atom changes from the ground state to an excited state.