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The Structure of Matter Atomic Models Subatomic Particles Forces Within the Atom Atomic Structure I. Structure of the Atom Chemical Symbols Subatomic Particles A. Chemical Symbols Capitals matter! Element symbols contain ONE capital letter followed by lowercase letter(s) if necessary. Metal that forms bright blue solid compounds. Co vs. CO Poisonous gas. B. Subatomic Particles ATOM ATOM NUCLEUS NUCLEUS ELECTRONS ELECTRONS PROTONS PROTONS NEUTRONS NEUTRONS POSITIVE CHARGE NEUTRAL CHARGE Most of the atom’s mass. NEGATIVE CHARGE NEGATIVE CHARGE in a neutral atom Atomic Number equals the # of... B. Subatomic Particles Quarks 6 types 3 quarks = 1 proton or 1 neutron He A. Atomic Mass atomic mass unit (u) 1 u = 1/12 the mass of a 1 proton = 1 u 12C atom 1 neutron = 1 u 1 u = 1.67 10-24 g © Addison-Wesley Publishing Company, Inc. B. Mass Number Sum of the protons and neutrons in the nucleus of an atom. Always a whole number. © Addison-Wesley Publishing Company, Inc. # of neutrons = mass # - atomic # C. Isotopes Atoms of the same element with different numbers of neutrons. Isotope symbol: Mass # Atomic # “Carbon-12” 12 6 C C. Isotopes © Addison-Wesley Publishing Company, Inc. Identity of the Atom: Understand that the number of protons determines the identity of an atom (an element). Understand that an atom of a given element may lose or gain electrons yet it still remains the same element. Mass of the Atom: Understand that only the total number of protons and neutrons determines mass. Reactivity of the Atom: Electrons determines properties. Chemical reactions occur in the electron cloud. The number of electrons in the outer energy level of the atom and the relative distance from the nucleus of these outer-energy level electrons determine how the atom will react chemically. Volume of the Atom: The volume of the electron cloud determines the volume of the atom. Atomic Number = Number of Protons - Elements are in order by atomic # - Identifies an element Mass Number = Protons and Neutrons added together Charge Mass Location Protons + 1 AMU Nucleus Neutrons 0 1 Amu Nucleus Electrons __ 0 AMU Electron Cloud Atomic Number Mass Number Protons Electrons K 5 Be 8 36 Neutrons Identify the element: •1.This element has 6 protons _____________________. •2.This element has 9 electrons ___________________. •3.This element has a mass of 11 amu and 4 electrons. _______________. •4.This element has a mass of 23 amu and 10 electrons. ______________. •5.This element has a mass of 20 amu and 9 electrons. _______________. •6This element has a mass of 19 amu and 8 electrons. _______________. •7.This element has 1 electron ___________________ C. Isotopes Average Atomic Mass reported on Periodic Table weighted average of all isotopes Avg. (mass # )(# of atoms) (mass # )(# of atoms) Atomic total # of atoms Mass C. Isotopes EX: About 8 out of 10 chlorine atoms are chlorine-35. Two out of 10 are chlorine-37. Avg. (35 u)(8 atoms) (37 u)(2 atoms) 35.4 u Atomic 10 atoms Mass Isotopes Name C-12 C-14 Cl-35 Cl-37 U-235 U-238 Atomic Mass # P # E N Three main subatomic particles Proton Neutron Electron Protons Positively charged Found in nucleus Has a mass of 1 amu The number of protons determines the identity of the atom The atomic number tells the number of protons Elements are made of atoms Hydrogen-1proton Helium-2 protons Lithium-3 protons The number of protons determines the identity of the element!! (atomic number) What is that other particle found in the nucleus? It’s a neutron! Neutrons have no charge – (they’re neutral) Neutrons have a mass of 1 amu Proton + neutron = mass number Electrons Electrons hang out in “orbitals” outside the nucleus of the atom Electrons have almost no mass The electron cloud is the majority of the volume of the atom ELECTRONS ARE NEGATIVELY CHARGED! More electron info! In a neutral atom, the number of electrons is equal to the number of protons When an atom gains or loses electrons, it is called an ion. The ionization process Now I’m a happy ion! I’m POSITIVE! And my outer shell is full, without that troublesome extra electron. This chloride ion has added an electron. It is a NEGATIVE ion! (note: the inner 2 electrons are not shown) Now I’m a happy ion!!! Sodium chloride-everybody’s happy! One lost…… (positive ion) One gained. (negative ion) Quick Review: • The three subatomic particles are proton, neutron and electron • Protons are positively charged, electrons are negative, neutrons are neutral • When an electron is lost or gained, the atom becomes an ion. Isotopes ► Atoms with the same number of protons but different numbers of neutrons are called isotopes. ► Isotopes are designated by the symbol and the mass number: H-1: 1 proton, no neutrons H-2: 1 proton, one neutron H-3: 1 proton, two neutrons It’s the Isotopes! What symbols represent ions? Elements on the left side of the periodic table will lose electrons to become positive ions – Examples: Ca2+, Na+,Fe3+,Fe2+,Al3+ Elements on the right side of the periodic table will gain electrons to become negative ions – Examples: F-, O2-, P3-, Cl- How big is the nucleus? If an atom was as big as a football field, the electrons would move over the entire field, while the nucleus would be the size of a lima bean in the middle of the field. If an atom was an elephant, the nucleus would be as big as a flea on the elephant How massive is the nucleus? Even though the nucleus is VERY small, it is VERY massive. Even though it’s the size of the flea, it would weigh as much as the elephant. And though the electrons take up as much space as the elephant, they would only weigh as much as the flea.