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Ions and Isotopes. Objective Students will be able to: use atomic symbols to represent different atoms and their isotopes. Identify and define ions of different elements. Some definitions. Ion - an atom that has a positive or negative charge.
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Ions and Isotopes Objective Students will be able to: use atomic symbols to represent different atoms and their isotopes. Identify and define ions of different elements
Some definitions • Ion - an atom that has a positive or negative charge How does something have a positive or negative charge? Number of protons and electrons has to be different!
How can an atom become an ion? • By gaining or losing electrons Losing Electrons= CATION Gaining Electrons= ANION
Cation • Positive charge • Formed by the atom losing electrons A neutral atom of sodium loses an electron and becomes Na+1 How many electrons does Li+1 have? Mg+2?
Anion • Negative charge • Formed by the atom gainingelectrons Chlorine gains one electron and becomes Cl-1 How many electrons does Br-2 have? F-1??
Why do atoms become ions? • Atoms want to have a full outer shell (orbital) • one electron in outer shell will lose the electron. • all but one electron will gain one. Which is likely to become a cation? Which is likely to become an anion?
Summary of Ions • Loseelectrons- become positive, which is a cation • Gainelectrons- become negative, which is an anion • Electrons are gained or lost in the outermost shell • These are called valence electrons
Atomic Notation Mass number= protons + neutron Element Symbol Atomic number= Protons P= N= E= 7 7 7 20 20 20 P= N= E=
Isotopes • Isotopesare atoms of the same element that have different numbers of neutrons. • The mass number of an isotope tells you the number of protons plus the number of neutrons. Difference? Similarities? http://web.visionlearning.com/custom/chemistry/animations/CHE1.3-an-isotopes.shtml H-1 H-2 H-3
Learning Check Naturally occurring carbon consists of three isotopes, 12C, 13C, and 14C. State the number of protons, neutrons, and electrons in each of these carbon atoms. 12C 13C 14C 6 6 6 #p _______ _______ _______ #n _______ _______ _______ #e _______ _______ _______
Solution 12C 13C 14C 6 6 6 #p 6 6 6 #n 6 7 8 #e 6 6 6
Heavy WaterApplication of isotope • Duterium- 21H can bind with oxygen • Only occurs 1 in every 3200 molecules • Concentrated heavy water is used for development of nuclear weapons • Can be poisonous to plants and animals.
Cobalt-60Application of isotope • Has one extra neutron in the nucleus • Radioactive and emits gamma radiation, which can pass through materials easily • Sterilizes medical equipment and kills harmful bacteria