The Atom

AMU = atomic mass unit Part Where Mass Charge proton electron Clouds (energy levels) outside the nucleus 1/1800 th AMU neutron no charge AMU = atomic mass unit

~1800 electrons 1 proton

Parts of the Atom

Box on the Periodic Table

Energy Levels 1st energy level must fill with 2 3rd energy level is not filled 2nd energy level Is full with 8

Isotopes of Hydrogen H-1 H-2 H-3

Warm- Up: Isotopes of Magnesium Magnesium has three isotopes, Mg−24, Mg−25, and Mg−26. The percentage of each in order is 78.70%, 10.13%, 11.17%. Calculate the relative atomic mass of Magnesium. 24 x .7870 = 18.88 25 x .1013 = 2.532 26 x .1117 = 2.904 18.88 2.532 + 2.904 24.32

Bohr Diagrams Find the element on the Periodic Table Put the name above and the symbol below the space for your diagram Find the #of protons Round the atomic mass to closest whole # and subtract the # of protons for # of neutrons Draw the electrons in their shells.

Warm-up #1 What is the common name of the element illustrated to the right? What is the symbol of this element? What is the atomic number of this element? The atomic number tells us how many _____are in this atom. What is the atomic mass of this element? The atomic mass tells us how many ____are in this atom. How many electrons are in this atom? Draw a Bohr Diagram of this atom (the high school way)

Warm up: Bohr Diagram In your notebook, draw the following atom the high school way: Argon

The HIGHSCHOOL Way Argon 18P 22N 8 8 2 Kr

Warm Up: What are three ways that an atom can be drawn to show the same information?

ISOTOPES To write the name of an isotope, we write the name of an element followed by its mass number, eg. Carbon-14 (which contains 6 protons and 8 neutrons in each atom). Did you know? Some isotopes are radioactive, meaning they give off radiation through a nuclear change, while others are known as stable, meaning they do not give off any radiation, Any atom that has an atomic number of 83 or higher is also radioactive, regardless of what isotope it is. Radioactive atoms and isotopes are dangerous to anything living thing except in the smallest possible amounts

Calculate the atomic mass of Carbon

Carbon There are three naturally occurring isotopes of carbon on Earth: 99% of the carbon is carbon-12 1% is carbon-13 carbon-14 occurs in trace amounts, e.g. making up as much as 1 part per trillion (0.0000000001%) of the carbon in the atmosphere. The half-life of carbon-14 is 5,730±40 years. It decays into nitrogen-14 through beta decay.

Otzi- found in a receding glacier 3300 BC determined by carbon dating Oldest natural human mummy Found in 1991 in Italian Alps where a glacier had receded Ötzi was a high-altitude shepherd Last meal was deer meat; hair samples gave clues about his diet

Otzi the Iceman

Which of the following are isotopes of each other? (a) An atom with 17 protons and 18 neutrons? (b) An atom with atomic number 16 and atomic mass 32? (c) An atom with atomic number 16 and 18 neutrons? (d) An atom with 16 protons and 18 neutrons? (e) An atom with 17 protons and 20 neutrons? (f) An atom with atomic number 16 and atomic mass 33? (g) An atom with 15 protons and 16 neutrons? Answer key: a & e; b, c, & f; g

Shaping Up Reflection Heart - One thing I love about this topic… Square- Four strategies that would have really worked in learning this material… Triangle- Three things that I’ve learned… Circle- One thing that is going around in your head…

The period # (row)on the Periodic Table of Elements tells you how many energy levels a atom has.

Valence Electrons Electrons in the outer shell Determines which elements will react with each other Chemistry happens here Full when it has 8 electrons (2 in the case of hydrogen and helium) An atom will either lose all of its valence electrons or gain to equal 8 during chem. reactions (becomes happy) Metals usually lose electrons—Why? Nonmetals usually gain electrons

Summary of Periodic Table Trends Moving Left --> Right Atomic Radius Decreases Ionization Energy Increases Electronegativity Increases Moving Top --> Bottom Atomic Radius Increases Ionization Energy Decreases Electronegativity Decreases

Half-life The half-life describes the amount of time needed for half of a sample of unstable atoms or particles to undergo decay. Thallium-208, for example, decays into lead-208 with a half-life of 3.05 minutes. This means that half of a sample of thallium-208 will decay into lead-208 over the course of 3.05 minutes. Scientists cannot predict when a particular atom or particle will decay. They only know that, on average, half of a sample will decay during the span of one half-life. 3.08 min 3.08 min