1 the physical setting chemistry 2 i. atomic concepts

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  • The Physical SettingChemistry

  • I. Atomic Concepts

  • The modern model of the atom has evolved over a long period of time through the work of many scientists. Democritus matter is made up of particles called atomsDalton atoms of the same element are alike solid indivisible spheresThomson discovers electrons plum pudding modelRutherford gold foil experiment discovers heavy, + charge nucleus mostly empty spaceBohr electrons orbit the nucleus

  • Regents Question: 08/02 #1Subatomic particles can usually pass undeflectedthrough an atom because the volume of an atomis composed of(1) an uncharged nucleus(2) largely empty space(3) neutrons(4) protons

  • Regents Question: 01/03 #62-64One model of the atom states that atoms are tiny particles composed of a uniform mixture of positive and negative charges. Scientists conducted an experiment where alpha particles were aimed at a thin layer of gold atoms.Most of the alpha particles passed directly through the gold atoms. A few alpha particles were deflected from their straight-line paths. An illustration of the experiment is shown below.

  • Regents Question contdMost of the alpha particles passed directly through the gold atoms undisturbed. What does this evidence suggest about the structure of the gold atoms? A few of the alpha particles were deflected. What does this evidence suggest about the structure of the gold atoms? How should the original model be revised based on the results of this experiment? Most of the atom is empty space.There is central + charge. The nucleus is +.The atom is not a uniform mixture of + and - charge. Positive charge is located in a heavy central mass.

  • Regents Question: 06/03 #67John Dalton was an English scientist who proposed that atoms were hard, indivisible spheres. In the modern model, the atom has a different internal structure.Identify one experiment that led scientists to develop the modern model of the atom.Rutherfords gold foil experiment

  • Regents Question contdJohn Dalton was an English scientist who proposed that atoms were hard, indivisible spheres. In the modern model, the atom has a different internal structure.Describe this experiment.

    State one conclusion about the internal structure of the atom, based on this experiment.Most of the atom is empty space.Rutherfords shot alpha particles a piece of gold foil. Most of the alpha particles went through, some were deflected and some were reflected.

  • In the wave-mechanical model (electron cloud model), the electrons are in orbitals, which are defined as the regions of the most probable electron location (ground state). An orbital is the area of highest probability of finding an electron.

  • Regents Question: 06/03 # 5The region that is the most probable location of an electron in an atom is(1) the nucleus(2) an orbital(3) the excited state(4) an ion

  • Regents Question: 06/02 #2The modern model of the atom shows that electrons areorbiting the nucleus in fixed pathsfound in regions called orbitalscombined with neutrons in the nucleuslocated in a solid sphere covering the nucleus

  • Each atom has a nucleus, with an overall positive charge, surrounded by one or more negatively charged electrons.

  • The proton is positively charged, and the neutron has no charge. The electron is negatively charged. ChargeMass

  • The mass of each proton and each neutron is approximately equal to one atomic mass unit. An electron is much less massive than a proton or a neutron. ChargeMass

  • Regents Question: 06/03 #2Which subatomic particle has no charge?(1) alpha particle(2) beta particle(3) Neutron(4) electron

  • Subatomic particles contained in the nucleus include protons and neutrons. Particles in the nucleus (protons and neutrons) are called nucleonsThe mass of the atoms is concentrated in the nucleusElectrons are not found in the nucleus, they orbit the nucleus.The net charge of the nucleus is positive (+)

  • Regents Question: 01/03 #1Which statement best describes electrons?They are positive subatomic particles and are found in the nucleus.They are positive subatomic particles and are found surrounding the nucleus.They are negative subatomic particles and are found in the nucleus.They are negative subatomic particles and are found surrounding the nucleus.

  • Regents Question: 06/02 #58-60In the modern model of the atom, each atom is composed of three major subatomic (or fundamental) particles.Name the subatomic particles contained in the nucleus of the atom.

    State the charge associated with each type of subatomic particle contained in the nucleus of the atom.

    What is the net charge of the nucleus?Proton and neutronProton is positive and the neutron is neutralPositive

  • Protons and electrons have equal but opposite charges. The number of protons equals the number of electrons in an atom. # of protons = # of electronsTherefore, atoms are electrically neutral.

  • Atomic Mass-number of nucleons (protons + neutrons)Atomic number # of protons in the nucleus.

    # neutrons = mass # - atomic #

  • The atomic number for an element cannot change but its mass number can.Atomic Number The number of protons in the nucleus of an atomDetermines which elementMass NumberThe number of nucleons (protons + neutrons)# neutrons = mass # - atomic #

  • Regents Question: 01/03 #3In which list are the elements arranged in order of increasing atomic mass?Cl, K, ArFe, Co, NiTe, I XeNe, F, Na

  • Regents Question: 06/02 #33The number of neutrons in the nucleus of an atom can be determined byAdding the atomic number to the mass numberSubtracting the atomic number from the mass numberAdding the mass number to the atomic massSubtracting the mass number from the atomic number

  • Regents Question: 06/03 #1The atomic number of an atom is always equal to the number of its(1) protons, only(2) neutrons, only(3) protons plus neutrons(4) protons plus electrons

  • Regents Question: 06/03 #36The nucleus of an atom of K-42 contains(1) 19 protons and 23 neutrons(2) 19 protons and 42 neutrons(3) 20 protons and 19 neutrons(4) 23 protons and 19 neutrons

  • Regents Question: 08/02 #4What is the total number of protons in thenucleus of an atom of potassium-42?(1) 15(2) 19 (3) 39(4) 42

  • Electron Configuration tells us how many electrons in each principal energy level (shell).Atomic Number = 7Mass Number = 14

    7 protons7 neutrons7 electronsElectron configuration: 2-5

  • The electron configuration for the ground state of an atom is given on the Periodic Table of the Elements.Electron Configuration

  • Each electron in an atom has its own distinct amount of energy. When electrons are in their lowest energy state, it is called the ground stateThe ground state for Na is 2-8-1

  • The maximum number of electrons in a principal energy level (shell) is 2n2.

    Energy level (n)Maximum number of electrons (2n2)1228318432

  • Regents Question: 06/02 #1What is the electron configuration of a sulfur atom in the ground state?2-42-62-8-42-8-6Look at the Periodic Table of the ElementsIf you do not know the symbol for sulfur, check Table S

  • If an atom gains or loses electrons it is called an ion.

    Calcium loses 2 electrons it becomes Ca+2 ionFlourine gains one electron it becomes F-1Gaining is negative Losing is positive GIN LIP

  • When an electron in an atom gains a specific amount of energy, the electron is at a higher energy state (excited state). Possible excited states for Na are: 2-7-21-8-2

  • When an electron returns from a higher energy state to a lower energy state, a specific amount of energy is emitted. This emitted energy can be used to identify an element. Emission Spectrum

  • Regents Question: 01/03 # 2During a flame test, ions of a specific metal are heated in the flam of a gas burner. A characteristic color of light was emitted by these ions in the flame when the electronsGain energy as they return to lower energy levelsGain energy as they move to higher energy levelsEmit energy as they return to lower energy levelsEmit energy as they move to higher energy levels

  • Regents Question: 06/03 # 3When the electrons of an excited atom return to a lower energy state, the energy emitted can result in the production ofalpha particles(2) Isotopes(3) protons(4) spectra

  • The outermost electrons in an atom are called the valence electrons. In general, the number of valence electrons affects the chemical properties of an element. The ground state for Na is 2-8-1The valence shell is the third shell.The valence shell contains 1 electron.

  • Regents Question: 06/03 #51-52Base your answers to the next two questions on the electron configuration table shown below.What is the total number of valence electrons in an atom of electron configuration X? Which electron configuration represents the excited state of a calcium atom? Element Electron Configuration X 2 8 8 2 Y 2 8 7 3 Z 2 8 822-8-7-3

  • Regents Question: 08/02 #2What is the total number of electrons in thevalence shell of an atom of aluminum in theground state?8 2 3(4) 10

  • Regents Question: 06/02 #31In which shell are the valence electrons of the elements in Period 2 found?1234

  • Atoms of an element that contain the same number of protons but a different number of neutrons are called isotopes of that element. Isotopes of Hydrogen1H protium1 proton0 neutron2H deuterium1 proton1 neutron3H tritium1 proton2 neutrons

  • Regents Question: 01/03 #9An atom of

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