Presentation on theme: "Summary of the Atom atoms are the smallest particles that can be uniquely associated with an element Atoms cannot break down further by chemical means."— Presentation transcript:
1 Summary of the Atomatoms are the smallest particles that can be uniquely associated with an elementAtoms cannot break down further by chemical means.each element has unique atomsatoms are composed of e-, p and natoms are electrically neutral (# of e- = # of p)for a single element, isotopes differ only in number of n (neutrons)atoms have characteristic masses (atomic weights)atoms combine with one another in definite, whole number proportions to make compounds
2 ~ 10-10 m electron nucleus Mass > 10-26 kg Mass 9 x 10-31 kg Here we have arrived at the usual pictorial conception of an atom. It is a misleading picture, but a good aide memoir .Size 1 angstrom unit m.Components electrons negative charge. Very lightat centre the nucleus positive to balance the electron chargeessentially all the mass.It’s the nucleus we want to talk about . So let’s look a little closer at it.
3 ~ 1 – 7 x m (1 – 7 fermi)The nucleus is times smaller than the atom, and as we said contains essentially all the mass. You can now see that the usual picture of the atom is way out of scale.A better idea of scale is given if we consider the atom to be the size of the Sydney Olympic stadium.
4 If I represented the nucleus as a small ball, and threw it into the middle of the stadium, we get a better idea of the size of the nucleus relative to the atom.
5 atoms are dominantly empty space: The Spacious Atomatoms are dominantly empty space:electron orbitsIf an oxygen atom had a total radius of 100 km, the nucleus would be a ~1 m diameter sphere in the middle.
6 Electrons in OrbitIn a simplistic model, electrons float around the nucleus in energy levels called shells.electron orbitsAs the number of electrons increases, they start to fill shells farther out from the nucleus.In most cases, electrons are lost or gained only from the outermost shell.
7 AtomNucleusNot a European football field, but a real Australian rules footy fieldThis is the Melbourne CG, and is the size of the
10 Mass of an electron is approximately 1/1840th of a proton or neutron. Mass of a neutron is very close to the mass of a proton.1 atomic mass unit (amu or u)=x10-24g1 g= x1023amuamu is defined by assigning a mass of exactly 12 amu to an atom of C-12 isotope.
11 1 amu (atomic mass unit) is… 1/12th of the mass of one carbon-12 atom.
12 Most of the mass of the atom is… formed by the nucleus.
13 Subatomic Particles Particle Symbol Charge Relative Mass(unit) Electron eProton pNeutron n
14 Atomic Number, Z (nuclear charge) is the total number of protons in the atom.Symbol11NaAtomic NumberAtoms are identified by their proton numbers.
15 All atoms of an element have the same number of protons 11Na11 protonsSodium
16 Number of Electrons If an atom is neutral ; The net charge on the atom is zeroNumber of protons = Number of electronsAtomic number = Number of electrons in a neutral atom
17 Ionshave a net electrical charge since the total number of electrons isn’t equal to the number of protons.can be anions (e->p+ ;formed as a result of gaining electrons; negatively charged), cations (p+>e-;formed as a result of losing electrons; positively charged).e- + q(charge of the ion) = proton number
18 In chemical rxns, atoms never gain or lose protons In chemical rxns, atoms never gain or lose protons. It’s the interaction of electrons.
19 Mass Number, A (nucleon number) Counts the numberofprotons and neutronsin an atomA= p+ + n0Protons and neutrons (together) are called “nucleons.”
20 11 Atomic Symbols 23Na (A)mass number (Z)atomic number sodium-23 Show the mass number and atomic numberGive the symbol of the element(A)mass number23Na11(Z)atomic numbersodium-23
21 12C 13C C Notation for Atoms only one isotope of carbon all isotopes of carbon
22 Basic Definitions “atomic number” = number of protons in the nucleus; “mass number” = sum of protons + neutrons in the nucleus“isotopic mass” = mass of a single isotope
23 16 31 65 8 15 30 More Atomic Symbols O P Zn 8 p+ 15 p+ 30 p+ O P Zn8 p p+ 30 p+8 n 16 n 35 n8 e e e-
24 Learning check For the ion find Nuclear charge Mass number Electron numberNeutron number
25 Learning checkFind the value of unknown quantities in the table given below.b) Classify each particle, X, Y, and Z as Cation, Anion and Neutral atom.
26 Homework!Prepare the flash cards having the symbol of the atom on one side and the name on the other side for the first 20 elements on Page 33 in your textbook.
27 IsotopesAtoms with the same number of protons, but different numbers of neutrons.Atoms of the same element (same atomic number) with different mass numbersIsotopes of chlorine35Cl 37Clchlorine chlorine - 37
28 Isotopes of Hydrogen element has the biggest abundance in nature.
29 Learning Check 1 An atom of zinc has a mass number of 65. A. Number of protons in the zinc atom1) ) ) 65B. Number of neutrons in the zinc atomC. What is the mass number of a zinc isotopewith 37 neutrons?1) ) ) 67
30 Solution An atom of zinc has a mass number of 65. A. Number of protons in the zinc atom1) 30B. Number of neutrons in the zinc atom2) 35C. What is the mass number of a zinc isotopewith 37 neutrons?3) 67
31 Learning Check 2Write the atomic symbols for atoms with the following:A. 8 p+, 8 n, 8 e- ___________B. 17p+, 20n, 17e- ___________C. 47p+, 60 n, 47 e- ___________
32 Solution B. 17p+, 20n, 17e- 37Cl 17 47 16O A. 8 p+, 8 n, 8 e- 8 C. 47p+, 60 n, 47 e- 107Ag47
33 Learning Check 3 16 14 14 An atom has 14 protons and 20 neutrons. A. Its atomic number is1) ) ) 34B. Its mass number isC. The element is1) Si 2) Ca 3) SeD. Another isotope of this element is1) 34X 2) 34X 3) 36X
34 Solution 14 An atom has 14 protons and 20 neutrons. A. It has atomic number1) 14B. It has a mass number of3) 34C. The element is1) SiD. Another isotope of this element would be3) 36X14