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S2 Science Atomic Structure LEARNING INTENTION • We are learning about atomic structure SUCCESS CRITERIA • I can state that all matter is made up of atoms and that • • • a substance that is made up of the same kind of atoms is an element I can describe the basic structure of an atom and state the location and charge of the proton, electron and neutron within the atom structure I can state the relative masses of the proton, neutron and electron. I can explain what is meant by atomic number and state that all elements are arranged in order of increasing atomic number in the Periodic Table SUCCESS CRITERIA • I can state that the mass number is the number of protons plus the • • • • number of neutrons present in an atom I can use nuclide notation to present information about atomic and mass numbers of atoms I can explain what is meant by the term isotope I can state that the electrons of an atom are arranged in energy levels I can state that an atom is neutral and explain why Modern Atomic Theory • All elements are made of identical tiny particles called atoms. • At first scientists thought atoms were solid spheres. Modern Atomic Theory • All elements are made of identical tiny particles called atoms. • At first scientists thought atoms were solid spheres. • We now know that this is not true. Atoms are made up of smaller particles called protons, electrons and neutrons. Modern Atomic Theory • The protons and • neutrons are in the nucleus. The electrons orbit around the nucleus Modern Atomic Theory Particle Charge Proton Neutron electron Use Standard Chemistry p23 Mass (amu) Found where? Modern Atomic Theory Particle Charge Proton +1 Neutron electron Use Standard Chemistry p23 Mass (amu) 1 Found where? nucleus Modern Atomic Theory Particle Charge +1 Mass (amu) 1 Proton Neutron nucleus 0 1 nucleus electron Use Standard Chemistry p23 Found where? Modern Atomic Theory Particle Charge +1 Mass (amu) 1 Proton nucleus Neutron 0 1 nucleus electron -1 1/1840 Outside nucleus Use Standard Chemistry p23 Found where? Modern Atomic Theory • The ATOMIC NUMBER is equal to • The MASS NUMBER is • The number of electrons in an atom is equal to • The number of neutrons in an atom is equal to Modern Atomic Theory • The ATOMIC NUMBER is equal to the number of • protons in an atom The MASS NUMBER is • The number of electrons in an atom is equal to • The number of neutrons in an atom is equal to Modern Atomic Theory • The ATOMIC NUMBER is equal to the number of • • protons in an atom The MASS NUMBER is the number of protons plus the number of neutrons The number of electrons in an atom is equal to • The number of neutrons in an atom is equal to Modern Atomic Theory • The ATOMIC NUMBER is equal to the number of • • • protons in an atom The MASS NUMBER is the number of protons plus the number of neutrons The number of electrons in an atom is equal to the number of protons The number of neutrons in an atom is equal to Modern Atomic Theory • The ATOMIC NUMBER is equal to the number of • • • protons in an atom The MASS NUMBER is the number of protons plus the number of neutrons The number of electrons in an atom is equal to the number of protons The number of neutrons in an atom is equal to the mass number – the number of protons Modern Atomic Theory • Nuclide notation can be used to show the number of protons, neutrons and electrons in an atom eg Mass number 37 17 Atomic number Cl Modern Atomic Theory • Atomic number = number of protons • Number of protons = number of electrons • Mass number = protons + neutrons • Number of neutrons = mass number – atomic number Modern Atomic Theory 37 17 Cl • Number of protons = • Number of electrons = • Number of neutrons = Modern Atomic Theory 37 17 Cl • Number of protons = 17 • Number of electrons = • Number of neutrons = Modern Atomic Theory 37 17 Cl • Number of protons = 17 • Number of electrons = 17 • Number of neutrons = Modern Atomic Theory 37 17 Cl • Number of protons = 17 • Number of electrons = 17 • Number of neutrons = 20 Modern Atomic Theory Element 24 12 80 35 Atomic number Mass number 19 40 protons electrons neutrons Mg Br 9 10 Modern Atomic Theory Element 24 12 80 35 Mg Atomic number Mass number protons electrons neutrons 12 Br 19 40 9 10 Modern Atomic Theory Element 24 12 80 35 Mg Atomic number Mass number 12 protons electrons neutrons 12 Br 19 40 9 10 Modern Atomic Theory Element 24 12 80 35 Mg Atomic number Mass number 12 protons electrons neutrons 12 12 Br 19 40 9 10 Modern Atomic Theory Element 24 12 80 35 Mg Atomic number Mass number 12 24 19 40 protons electrons neutrons 12 12 Br 9 10 Modern Atomic Theory Element 24 12 80 35 Mg Atomic number Mass number 12 24 19 40 protons electrons neutrons 12 12 12 Br 9 10 Modern Atomic Theory Element 24 12 80 35 Atomic number Mass number protons electrons neutrons Mg 12 24 12 12 12 Br 35 80 35 35 45 19 40 9 10 Modern Atomic Theory Element 24 12 80 35 Atomic number Mass number protons electrons neutrons Mg 12 24 12 12 12 Br 35 80 35 35 45 K 19 40 9 10 Modern Atomic Theory Element 24 12 Atomic number Mass number Mg 12 24 12 12 12 Br 35 80 35 35 45 K 19 40 80 35 40 19 protons electrons neutrons 9 10 Modern Atomic Theory Element 24 12 Atomic number Mass number Mg 12 24 12 12 12 Br 35 80 35 35 45 K 19 40 19 19 21 80 35 40 19 protons electrons neutrons 9 10 Modern Atomic Theory Element 24 12 Atomic number Mass number Mg 12 24 12 12 12 Br 35 80 35 35 45 K 19 40 19 19 21 F 9 80 35 40 19 9 protons electrons neutrons 9 10 Modern Atomic Theory Element 24 12 Atomic number Mass number Mg 12 24 12 12 12 Br 35 80 35 35 45 K 19 40 19 19 21 9 19 9 9 10 80 35 40 19 19 9 F protons electrons neutrons Arranging Electrons Target Model • The target model of an atom is a picture that shows clearly how the electrons in an atom are arranged in separate energy levels. Target Model Example • An atom with 15 • electrons Only 2 electrons can fit into the first energy level. 15+ Target Model • Only 2 electrons can • fit into the first energy level. 8 electrons fit into the next shell 15+ Target Model • Only 2 electrons can • • fit into the first energy level. 8 electrons fit into the next shell The five remaining electrons fit into the third shell. 15+ Electron Arrangements • An electron arrangement is a sequence of numbers that says how many electrons are in each energy level of an atom starting from the inside and working outwards. 15+ 2,8,5 Electron Arrangements • Li • Na •F • Si Electron Arrangements • Li • Na •F • Si 2,1 Electron Arrangements • Li • Na •F • Si 2,1 2,8,1 Electron Arrangements • Li • Na •F • Si 2,1 2,8,1 2,7 Electron Arrangements • Li • Na •F • Si 2,1 2,8,1 2,7 2,8,4 • The number of electrons in the outer shell is the same as the group number. Target Pictures • A target picture of an atom shows clearly how the electrons are arranged in the separate energy levels. Drawing Target Pictures • Potassium Drawing Target Pictures • Potassium 19+ 2,8,8,1 Drawing Target Pictures • Sulphur Drawing Target Pictures • Sulphur • The first 4 electrons in the shell are unpaired. Any further electrons form pairs. 16+ 2,8,6 Isotopes • Isotopes are atoms of the same element but with a different mass number. Isotope 63 29 65 29 Cu Cu protons electrons neutrons Isotopes • Isotopes are atoms of the same element but with a different mass number. Isotope 63 29 65 29 Cu Cu protons electrons neutrons 29 Isotopes • Isotopes are atoms of the same element but with a different mass number. Isotope 63 29 65 29 Cu Cu protons electrons neutrons 29 29 Isotopes • Isotopes are atoms of the same element but with a different mass number. Isotope 63 29 65 29 Cu Cu protons electrons neutrons 29 29 34 Isotopes • Isotopes are atoms of the same element but with a different mass number. Isotope 63 29 65 29 protons electrons neutrons Cu 29 29 34 Cu 29 29 36 Isotopes • They have different mass numbers because they have a different number of neutrons. Isotopes • They have different mass numbers because they have a different number of neutrons. Isotopes • In the data book, the mass number of each element is given as an average of all the isotopes. Isotopes • In the data book, the mass number of each element is given as an average of all the isotopes. • This is called the relative atomic mass Isotopes • In the data book, the mass number of each element is given as an average of all the isotopes. • This is called the relative atomic mass • It does not need to be a whole number eg chlorine • Chlorine has 2 isotopes 35 17 Cl 37 Cl 17 eg chlorine • Chlorine has 2 isotopes p =17 e =17 n =18 35 17 Cl 37 Cl 17 p =17 e =17 n =20 eg chlorine • Chlorine has 2 isotopes p =17 e =17 n =18 35 17 Cl 75% 37 Cl 17 25% p =17 e =17 n =20 eg chlorine • Chlorine has 2 isotopes p =17 e =17 n =18 35 17 Cl 37 17 75% Weighted average Relative atomic mass Cl p =17 e =17 n =20 25% (75 X 35) + (25 X 37) / 100 35.5