The Three Primary Subatomic Particles... Protons (positive) Neutrons (neutral) Electrons (negative) Note: protons and neutrons are made up of even smaller particles called Quarks # of protons = the atomic number Atomic number = # of protons # of protons determines which element it is! Who is element # 15? Phosphorus How many protons does lithium have? 3 What is the atomic number of tin? 50 Number of neutrons can vary, even for the same element. Neutrons affect the atomic mass Isotopes Elements can have many different isotopes same # of protons (same element) different # of neutrons (isotope) Carbon-12, Carbon-13, Carbon-14, Uranium-235, Uranium-238 Neutrons contribute to the “Strong Force” that holds the nucleus together. Sum of the protons and neutrons Electrons are not included Too small (1/2000) What is the atomic mass of this atom? A neutral atom has no charge. positive charges = negative charges. A neutral atom has the same # of electrons as protons How many electrons does this atom have? Atomic Mass Protons + Neutrons #Protons 23 11 Na Element Symbol Atomic Number # Neutrons = Atomic Mass – Atomic Number Find the number of protons, neutrons and electrons in the following elements 35 Cl 17 243 Am 95 35 17 Cl 243 95 Am 17 protons 17 electrons 35-17 = 18 neutrons 95 protons 95 electrons 243-95 = 148 neutrons If an atom is not neutral, then it has a charge. Ion Charged particle This atom has: 3 protons (+++) 2 electrons (- -) Net charge is +1 and it is written as Li+1 It is called a Cation If an atom is not neutral, then it has a charge. Ion Charged particle This atom has: 9 protons (+++++++++) 10 electrons (- - - - - - - - - -) It is written as F-1 It is called an Anion How many protons? How many neutrons? How many electrons (if the atom is neutral?) How many protons? – The atomic number How many neutrons? – Atomic mass minus atomic number How many electrons (if the atom is neutral?) – Same as # of protons Ion: Charged Particle Anion: Negatively Charged Particle Cation: Positively Charged Particle Isotope: Same # of Protons, Different # of Neutrons. Atomic number: # of Protons Atomic mass: Protons + Neutrons Just like members of a family, certain elements of the periodic table share similarities. Like good looks! Families of elements are groups of elements that have similar properties. Groups can be a single column or a whole section of the periodic table. Let’s start with the big groups first. Similar metals are grouped together. Two groups of metals are located on the left side of your periodic table. Some are located on the right side of the table left of the stair steps. Most are located in the middle of the periodic table. The elements that are usually poor conductors of heat and electricity. First notice the location of nonmetals. Second notice what these elements are. The elements that are intermediate conductors of heat and electricity. (can do it but only under certain conditions) Sometimes called Metalloids Found by the “stair-step” divider between metals and non-metals Specific groups that have similar properties are in the columns on the periodic table. These are the numbers 1-18 or 1A -8A across the top of the table. sodium and potassium Brainiac The highly reactive metallic elements located in Group 1 of the periodic table. Tend to lose 1 electron They are Cations (+1 charge) React with water Alkali Metals are located on the left edge of the periodic table Lumps of Calcium The reactive metallic elements located in Group 2 of the periodic table. Tend to lose 2 electrons They are Cations (+2 charge) Do not react with water. The alkaline-earth metals make up the second column of elements from the left edge of the periodic table. These are metallic elements in Group 3-12 of your periodic table. They are “transition metals” because they shift from being similar to group 2 (alkali metals) over to being like group 13 moving left to right. Halogen Lamps Bromine burning The highly reactive elements located in Group 17 of the Periodic table. Are all diatomic(F2, Cl2, Br2, I2) Atoms Tend to gain 1 electron They are Anions (-1 charge) The halogens are in the second column from the right of the periodic table. No not kings and queens. The unreactive gaseous elements located on Group 18 of the periodic table. Noble gases are located on right edge of the periodic table. And on the throne when kings and queens fart ! Diatomic = two atoms There are 7 diatomic atoms N2, O2, F2, Cl2, Br2, I2, H2 Remember them by the rule of “7” Starts with element 7 = Nitrogen Forms a 7 through oxygen and down to iodine The 7th diatomic element is hydrogen Man-Made Elements • Which are the man-made or synthetic Elements? • How are synthetic elements made? Cyclotron, protons, alpha particles and heavy atoms • Why do scientists continue to try to make elements?