Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Assign # 40 pts Notes – Chapter 4; Unit 2 Section A Atomic Structure Atoms • Atoms - The building blocks of matter. • Aristotle “Matter is continuous and can be subdivided endlessly into smaller and smaller parts” • Democritus “Subdivision of matter will eventually end” • “Atomos” – its name means “uncut”. It is the smallest part of an element which has the properties of that element. Atom Sub-atomic Particles (3) Building blocks of atoms 1) Protons (+) p+ 2) Electrons (-) e- 3) Neutrons (no charge) no Nitrogen • Atoms - The building blocks of matter. The smallest part of an element with the properties of that element p+ e- no Nucleus – The central core of an atom made up of protons and neutrons. Contains almost all of an atom’s mass p+ no • AMU – Atomic Mass Unit Used for comparing the mass of atoms and particles (Also called daltons Da) Protons – Positively charged particles in the nucleus. eAMU = 1 Neutrons – Neutrally charged (no charge) particles in the nucleus. AMU = 1 Electrons – Negatively charged particles. Orbit the nucleus in shells or clouds 1/1836 AMU Nitrogen p+ no 1 AMU = 1/12 the mass of a neutral Carbon atom • Atoms are mainly empty space with 99.9% of their mass in the nucleus The nucleus is (+) positively charged because of its protons. • In a neutral atom the proton # = electron # • B = Boron = __p+, __e• Cl = Chlorine = ____p+, ____e- e- p+ • Atoms are mainly empty space with 99.9% of their mass in the nucleus The nucleus is (+) positively charged because of its protons. • In a neutral atom the proton # = electron # • B = Boron = __p+, __e• Cl = Chlorine = ____p+, ____e- p+ e- Atomic Number • Atomic Number – The number of protons in an atom’s nucleus. It is used to determine and #1=H– describe each #2 = He – element #3 = Li – Dalton’s Atomic Theory • 1) All elements are composed of indivisible particles called atoms • 2) Atoms of different elements can physically mix together or chemically combine in whole number ratios to form compounds • 3) Atoms of the same element are identical. The atoms of any one element are different from those of any other element. • 4) Chemical reactions occur when atoms are separated, joined, or rearranged. Atoms are never changed into atoms of another element as a result of chemical reactions. Atomic Mass (Weight) • Atomic Weight (Mass)= Number of protons and neutrons in an atom’s nucleus. Subtracting the atomic mass and atomic number tells the number of neutrons Neutrons give the atom mass but no charge Helium = He = Atomic # 2 Atomic mass = 4.0026 2 p+, 2 no Atomic mass – Atomic # = # no In neutral atoms # of p+ = # of e- 15 Atomic number Chemical symbol – one or two letters for each element p+ = e-= no = 30.974 Atomic mass Atomic Particles • Lithium = Atomic Mass = • Chlorine = Atomic Mass = Mass # (rounded) = mass = -# Mass # (rounded) p+ = e- = no = = mass = -# p+ = e- = no = Isotopes – Atoms of the same pair of elements with different #’s of neutrons 14 C 6 __________ 8 neutrons 13 C 6 _______ 7 neutrons 12 Mass number C 6 Atomic number ______ 6 neutrons Same elements, same # protons and electrons, different # neutrons Isotopes – Atoms of the same pair of elements with different #’s of neutrons 14 13 C C 6 __________ 8 neutrons 6 _______ 7 neutrons 12 Mass number C 6 Atomic number ______ 6 neutrons Same elements, same # protons an electrons, different # neutrons C 12 = C 13 = C 14 = 98.89 % x 12 = 1.1 % x 13 = .0000000001% x 14 = . 11.668 .1443 .0000000000014 = 12.0111 = 12.011 Isotopes • Chemical symbol shorthand: Shows symbol with atomic number and mass number Isotope name is from mass number 17 = Atomic # Cl 35 = Mass # Chlorine-35 Isotopes – Atoms of the same pair of elements with different #’s of neutrons 14 C 6 __________ 8 neutrons 13 C 6 _______ 7 neutrons 12 Mass number C 6 Atomic number ______ 6 neutrons Same elements, same # protons and electrons, different # neutrons Carbon-14 Carbon-13 Carbon-12 Ions – Charged atoms or groups of atoms • Most atoms are not in the neutral state. Atoms will lose, gain, or share electrons to become stable Sodium atoms have a tendency to lose electrons. Na 11p+ 11e- 11p+ 10e- = +1 Na + 1 = Cation (positive) Chlorine atoms have a tendency to gain electrons. Cl 17p+ 17e- 17p+ 18e- = -1 Cl - 1 = Anion (negative) Na +1 + Cl-1 = NaCl o Sodium Chloride is an Ionic Compound Ionic Bond – Positive (+) and negative (-) ions attract – formed by the transfer of valence electrons. Dalton’s Atomic Theory • 1) All elements are composed of indivisible particles called atoms • 2) Atoms of different elements can physically mix together or chemically combine in whole number ratios to form compounds • 3) Atoms of the same element are identical. The atoms of any one element are different from those of any other element. • 4) Chemical reactions occur when atoms are separated, joined, or rearranged. Atoms are never changed into atoms of another element as a result of chemical reactions. Discovering the Atom’s Sub-Atomic particles • 1897 Thompson discovered the electron • Cathode ray – Particles • 1/1840 mass of H atom Discovering the Atom Electrons • 1897 Thompson discovered the electron • Cathode ray – Particles • 1/1840 mass of H atom • Deflected negative source, attracted toward positive source Discovering the Atom Electrons • 1897 Thompson discovered the electron • Cathode ray – Particles • 1/1840 mass of H atom • Deflected negative source, attracted toward positive source • Devised “plum pudding” model Discovering the Atom Atomic nucleus • 1911 Rutherford used Alpha particles ( Helium atoms that have lost their two electrons and have double positive charges) to bombard a sheet of gold foil. • A small fraction bounced off the gold at very large angles Discovering the Atom Atomic nucleus • Proposed that the atom is mainly empty space • Positive charge and mass are concentrated in a small central core called the nucleus. Discovering the Atom Atomic nucleus • Proposed that the atom is mainly empty space • Positive charge and mass are concentrated in a small central core called the nucleus. Properties of Atoms • Atoms are distinguished from each other by their number of protons • This determines the different types of elements. • Atoms are mainly empty space with a concentrated core in the center Properties of Atoms • If an atom were the size of a football field the nucleus would be the size of a marble Properties of Atoms • If an atom were the size of a football field the nucleus would be the size of a marble . Periodic Table • The Periodic Table is an arrangement of elements into groups based on a set of repeating properties • It is based on the number of protons and the electron configuration Periodic Table • The Periodic Table is an arrangement of elements into groups based on a set of repeating properties • It is based on the number of protons and the electron configuration Valence electron Periodic Table • The Periodic Table is an arrangement of elements into groups based on a set of repeating properties • It is based on the number of protons and the electron configuration Periodic Table Period • Each horizontal row of the periodic table is called a period. • It is based on the number of electrons shells Periodic Table Group (family) • Each vertical column of the periodic table is called a group of family. • Elements within a group have similar chemical and physical properties • They are grouped by their number of outside electrons Periodic Table Group (family) • Each vertical column of the periodic table is called a group of family. • Elements within a group have similar chemical and physical properties • They are grouped by their number of outside electrons