Chapter 5 Electrons in Atoms

Warm-Up Carbon-14 has an Atomic Number of 6 and Mass of __________? Find the number of: Protons Neutrons Electrons What is the equation to find the number of neutrons? What is the equation, if given neutrons and protons, to find atomic mass? What is the charge of the nucleus of an atom? What is the charge of all electrons and neutrons in an atom? What is the charge of all electrons, protons and neutrons in an atom?

Warm-Up Carbon-14 has an Atomic Number of 6 and Mass of __________? Find the number of: Protons: 6 Neutrons: 8 Electrons: 6 What is the equation to find the number of neutrons? Neutrons = Atomic Mass – Atomic Number (number of protons) What is the equation, if given neutrons and protons, to find atomic mass? Neutrons + Protons = Atomic Mass What is the charge of the nucleus of an atom? Positive What is the charge of all electrons and neutrons in an atom? Negative What is the charge of all electrons, protons and neutrons in an atom? Neutral

Atoms and Their Interactions Elements A substance that can’t be broken down into simpler chemical substances Everything is made up of elements

Atoms Electron Energy Levels Each “dot” holds 2 electrons. Each level needs to be completely filled before moving on to the next level. Each level will fill with 1 electron per dot, before moving filling with a secondary electron

Atoms Electron Energy Levels - Order Aufbau Principal – Each electron occupies the lowest energy orbital possible 1S S Orbital – Holds 2 Electrons P Orbital – Holds 6 Electrons D Orbital – Holds 10 Electrons F Orbital – Holds 14 Electrons 2S 2P 3S 3P 3D 4S 4P 4D 4F 5S 5P 5D 5F 6S 6P 6D 6F

Atoms Electron Energy Level Example Argon: 18 Electrons Pauli Exclusion Principal – A maximum number of 2 electrons can occupy a single atomic orbital, but they must have different spins Hund’s Rule – Single electrons with the same spin must occupy each equal-energy orbital before additional electrons with opposite spins can occupy the oribtal. Electron Energy Level Example Argon: 18 Electrons The number of electrons is the Atomic Number 1S 2S 2P 2P 2P 3S 3P 3P 3P

Valence Electrons Valence Electrons Determine the chemical properties of an element Defined as the electrons in the atom’s outermost orbitals Use the Periodic Table Trick for most common valence electron For transition metals Draw/create the Electron Configuration Determine the outermost shell It might not be the last shell Those are your valence electrons Ex: Cu has an atomic number of 29 and the electron configuration is: 1S2 2S2 2P6 3S2 3P6 4S1 3D10(Exception to the Prediction) The OUTERMOST shell is 4S so Cu has 1 valence electron

Periodic Table Valence Electron Trick Number of valence electrons in that column 1 8 2 3 4 5 6 7

Lewis-Dot Structure / Electron-Dot Structure Find the Valence Electrons Draw the Element/Chemical Symbol Starting on the top of the symbol and working clockwise to all four sides, draw 1 dot for each of the electrons present. If there are more than 4 electrons present, then again, move around clockwise, until all electrons are used.

Lewis Dot Structures of the Element