Unit 2: Structure of atoms and ions

What makes up an atom? Nucleus (protons and neutrons) and electrons

Protons, electrons, and neutrons Charge Relative mass Proton Positive (+) 1 Neutron Neutral (no charge) Electron Negative (-) 1/2000

Neutral Atoms In neutral atoms (no charge), electrons (-) and protons (+) are equal Why? (+)2 + (-)2 = 0 (+)2 + (-)1 = +1 No charge (neutral) Positive charge

Protons, electrons, and neutrons Atomic number = # of protons If atom is neutral, it is the number of electrons too. Mass number

Protons, electrons, and neutrons Mass number = # protons + # neutrons Mass number

Warm-up Why do some atoms have charges while others are neutral? Name one element that has a different number of protons and neutrons. What would be the charge of Zinc if it had 28 electrons? What is the relative mass of protons, neutrons, and electrons?

Ions Ions are charged atoms Cations = positively (+) charged atoms Anions = negatively (-) charged atoms

Don’t Fall! Element Mass # of Protons # of Neutrons # of Electrons K 79.9 g/mol 35 Al+3 13 39.1 g/mol 19 20 19 Br 45 35 26.98 g/mol 14 10

Homework Element Mass # of Protons # of Neutrons # of Electrons N 30.97 g/mol 15 Na+1 11 O-2 17 18

Isotopes Same number of protons (and electrons), but different number of neutrons Isotopes are often unstable and radioactive! After first bullet: What would this affect mass number or atomic number? Same # protons

Summary Atom Neutral atom Same # of protons and electrons Ion Different # of protons and electrons Isotope Different # of protons and neutrons

How are electrons configured around the nucleus?

Electron Configuration Level State Neighborhood Sublevel Block Neighborhood House Orbital House Electrons People People

Levels There are 7 levels (neighborhoods) Each level is higher in energy and less stable. 1 1 2 3 4 5 6 7

Sublevels Each level (neighborhood) can have up to 4 sublevels (blocks)

Orbitals and Electrons Orbitals (houses) are where the electrons (people) are housed within a sublevel (block).

Mapping Electrons Electron Configuration is a way to map the location of electrons for an element. Mapping occurs from left to right, moving down the Periodic Table.

Electron Configuration Electron Configuration for Oxygen 1s 2 1 2s 2 1 4 3 2 1 2p

Checking Electron Configuration How many electrons does Oxygen have? Oxygen -1s22s22p4 2+2+4=8

Bohr Models A basic model of the atom. Protons, neutrons, and electrons Energy levels

How to Draw a Bohr Model Draw the nucleus. Write the # of protons and neutrons in the nucleus. Draw the electrons evenly distributing them throughout each level. Follow rules for # of electrons for each level.

Rules for Energy Levels Level 1 (closest to the nucleus) can hold a maximum of 2e. Level 2 can hold a max of 8e. Level 3 can hold a max of 18e. Level 4 can hold a max of 32e. You must fill one level before going on to draw the next level!

How to Draw a Bohr Model Bohr Model for Oxygen 8 p 8 n

Valence Electrons The highest energy level contains the valence electrons. Valence electrons participate in bond formation. Atoms are most stable when they have 8 valence electrons.

Valence Electrons 6 How many valence electrons does Oxygen have? 8 p

Valence Electrons +1 1 +2 +3 ±4 -3 -2 -1 8 2 3 4 5 6 7

Lewis Dot Diagrams Lewis Dot Diagrams shows only valence electrons. How to: Write the element symbol Determine the number of valence electrons Draw valence electrons around each side of the symbol.

Energy Exists in discrete units called quanta. Energy is a result of electrons moving. Electrons like to be close to protons (nucleus)

Gaining Energy Further from nucleus = higher energy

Losing Energy Closer to nucleus = lower energy

Losing Energy Produces electromagnetic radiation called photons.

Losing Energy This loss in energy emits electromagnetic radiation called photons. Photon=a packet of energy Responsible for visible light.

Wavelength Wavelength and frequency are inversely proportional.

Electromagnetic Spectrum