# Chapter 2 Topics: Elements and the Periodic Table Can you find the halogens? Alkali metals? Noble gases? Transition.

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Chapter 2 Topics: Elements and the Periodic Table http://www.youtube.com/watch?v=1PSzSTilu_s Can you find the halogens? Alkali metals? Noble gases? Transition metals? Alkaline earth metals? Lanthanides and actinides? Metals? Nonmetals? Semimetals or metalloids? Balancing Equations What coefficients balance this equation: Mg + Al 2 S 3 → Al + MgS Types of Reactions http://www.youtube.com/user/MarkRosengarten#p/c/65159266CFC74682/19/dxlWtsFinTM Classify the reaction type above. http://www.youtube.com/user/MarkRosengarten#p/c/65159266CFC74682/18/ QjVYz00-Kxc

ParticleChargeMassLocation Electron1/1800 Outside the nucleus Proton+11 Inside the nucleus Neutron01 + 1/1800Inside the nucleus Subatomic Particles!

Vocabulary, vocabulary, vocabulary The number on the Periodic table is the ATOMIC WEIGHT. This is an average mass of all the ISOTOPES that occur in nature. The number on the Periodic table is the ATOMIC WEIGHT. This is an average mass of all the ISOTOPES that occur in nature. Atomic mass or mass number is a WHOLE number that must be rounded from the number on the periodic table. It is the number of protons + the number of neutrons in an atom of the element.

Isotope Notation! Isotopes are atoms of the same element that have different MASSES. They have the same number of PROTONS, but different numbers of NEUTRONS. Isotopes are atoms of the same element that have different MASSES. They have the same number of PROTONS, but different numbers of NEUTRONS. Isotopes of an element have the same physical and chemical properties. They only have different MASSES!

40 20 Ca How many protons? What is the atomic number? What is the mass number? How many neutrons? How many electrons? (Hint: All atoms must be neutral!) 21 Ne How many protons? How many neutrons? How many electrons? 19 9 X How many protons? How many neutrons? What element is this? An isotope of an element has 3 protons and 4 neutrons. Write its isotope notation.

Lithium exists as two isotopes: lithium-7 and lithium-6 Lithium-7 has a mass of 7.015 amu and makes up 92.58% of lithium Lithium-6 has a mass of 6.015 amu and makes up 7.42% To calculate the average atomic mass of lithium, multiply the mass of each isotope by its abundance, then add these 2 values to each other What is the atomic weight of lithium (on the periodic table)? Which isotope is more abundant, lithium-6 or lithium-7?

Mass Defect There's actually one more reason why the mass isn't a whole number.... recall that the mass of a neutron isn't exactly 1 amu. And when protons and neutrons stick together to make a nucleus, a small amount of mass is converted to energy, making a very strong bond called strong nuclear force. E=mc 2

Atoms are neutral because they have the same number of protons and electrons. When an atom loses electrons it becomes a positively charged ion called a cation. When an atom gains electrons it becomes a negatively charged ion called an anion.

39 K + How many protons does this isotope have? How many neutrons? How many electrons does this ion have? 16 O 2- How many protons does this isotope have? How many neutrons? How many electrons does this ion have?

http://www.youtube.com/watch?v=1R7NiIum2TI And now, I am excited to present to you... MOLES!!!

1 mole = 6.02 x 10 23 atoms = the atomic weight in grams There are 6 conversion factors that can be made from these equalities. Can you write them all?

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