Elements and Periodic Table Chapter 3 Unit- Introduction to chemistry Mrs. Castro

Lesson 1 Pages 72 – 79 Introduction to Atoms

Introduction to atoms Atomic Theory This is the theory that explain with details the component of the atoms and their organization. Grew as a series of models that developed from experimental evidence. As more evidence was collected, the theory and models were revised.

Introduction to atoms Democritus – Greek philosopher – 430 B.C. Proposed that matter was formed of small pieces that could not be cut into smaller parts. He called the particles atoms – means “uncuttable” Atoms is the smaller particles that still can be consider an element. 1600 – people did experiments and the theory began to take shape.

Introduction to atoms John Dalton – English chemist Dalton’s Atomic Theory: All elements consist of atoms that cannot be divided. All atoms of the same element are exactly the same and have the same mass. Atoms of different elements are different and have different mass. An atom of one element cannot be changed into an atom of a different element by a chemical reaction. Compounds are formed when atoms of more than one element combine in a specific ratio.

Introduction to atoms J.J. Thomson – 1897 Discovered that the atoms contain negatively charged particles called electrons. He reasoned that atoms must also contain some sort of positive charge, balance the negative charge of the electrons.

Introduction to atoms Ernest Rutherford – 1911 Suggested that the atoms is mostly empty space but has a positive charge at its center (nucleus). He called the positively charged particles in an atom’s nucleus protons.

Introduction to atoms Niels Bohrs – 1913- Danish scientist Suggested that the electrons are found only in specific orbits around the nucleus. Each possible electron orbit in Bohr’s model has a fixed energy.

Introduction to atoms Cloud Model – 1920 Electron are moved rapidly within a cloudlike region around the nucleus. An electron’s movement is related to its energy level, or the specific amount of energy it has. Electrons at different energy levels are likely to be found in different places.

Introduction to atoms Modern model of atom James Chadwick – 1932 – English scientist Found a no electric charge particle. He called neutron. Modern model of atom At the center of the atom is a tiny, dense nucleus containing protons and neutrons. Surrounding the nucleus is a cloudlike region of moving electrons.

Introduction to atoms Model of Modern Atom:

Introduction to atoms Important details: Proton = p+, positive charge Electron = e-, negative charge Neutron = n, no charge The number of protons equals the number of electrons. As a result, the positive charge is equals to the negative charge. The charge balance, make the atom neutral. Neutrons don’t affect the charge of an atom because they have a charge of zero.

Introduction to atoms Answer the following questions: What is in the center of an atom? What particles we found inside the center of an atom? Where the electrons are found? Why the atom is neutral? What is the effect of the neutrons on the charge of an atom? If the atom has 8 p+, how many e- does it have? What is the atom’s charge?

Introduction to atoms Atomic mass (Z) = n + p+ Atomic number (A) = p+ The mass of the atom is in the nucleus. Atomic number (A) = p+ Atomic number = e- Answer: Z = A = Element name = Element symbol =

Introduction to atoms Identify Z, A and element name, electron’s quantity and proton’s quantity : A = atomic number Hydrogen Z = atomic mass e- = 1 p+ = 1

Introduction to atoms Remember: Atomic mass (Z) = n + p+ From this equation: n = p+ - atomic mass (Z) Atomic number (A) = p+ = e-

Introduction to atoms Complete the following table: Atom’s Name Symbol Atomic number Atomic mass e- p+ n 52 128 Sr 38 50 103 45 Pb 82 125 209 126 Zr 40 51

Introduction to atoms Answer Atom Name Symbol Atomic number Atomic mass e- p+ n Tellurium Te 52 128 76 Strontium Sr 38 88 50 Rhodium Rh 45 103 58 Lead Pb 82 207 125 Bismuth Bi 83 209 126 Zirconium Zr 40 91 51

Introduction to atoms Isotopes Atoms with the same number of protons and different numbers of neutrons. Isotopes are identified by its mass number or atomic mass. Examples: Carbon atomic number is 6. Protons = 6 C-12 C-13 C-14 n=12-6 n=13-6 n=14-6 6 7 8 Atom Isotope Isotope

Introduction to atoms Fill the blanks: The ______ is the very small, dense center of an atom. The positively charged particle of an atom is called ___________. A particle with no charge is ________. An _______ is the particle of an atom that moves rapidly in the cloudlike region around the nucleus. nucleus proton neutron electron

Introduction to atoms The ___________ tells the number of protons in the nucleus of every atom of an element. Atoms of the same element that have the same number of protons but diffrent numbers of neutrons are called _________. The sum of p+ and n in the nucleus of the atom is the _________. Atomic number isotopes Atomic mass

Perform all the excises. Introduction to atoms Read pages 73 to 79. Perform all the excises.

Organizing the Elements Lesson 2 Pages 80 - 87 Organizing the Elements

Organizing the elements 1860 – 63 elements were discovered. Dmitri Mendeleev discovered a set of patterns that applied to all the elements. He noticed that the pattern of properties appeared when he arranged the elements in order of increasing atomic mass. He found that the properties of the elements repeated. Properties studies: melting point, density , color and atomic mass.

Organizing the elements Mendeleev created the first Periodic Table in 1869. This is a table in which is an arrangement of elements showing the repeating pattern.

Organizing the elements As scientists discovered new elements and learned more about atomic structure, the periodic table changed. At the present, the Periodic Table is arranged in order of increasing atomic number. It is now know that the number of protons in the nucleus, given by the atomic number, determines the chemical properties of an element.

Organizing the elements

Organizing the elements

Organizing the elements Periodic Table Information; Atomic number - # p+ and e- Chemical symbol Is one or two letters. First letter is capital letter, second letter is lowercase letter. Is an abbreviation of the element’s name in English. Some of them, have symbols that are abbreviations of their Latin names. Atomic mass – n + p+

Organizing the elements Fing the element’s name or symbol. Element’ name Symbol Tin Na Barium Br Galium C Neon B Nickel Al

Organizing the elements Fing the element’s name or symbol. Element’ name Symbol Tin Sn Sodium Na Barium Ba Bromine Br Galium Ga Carbon C Neon Ne Boro B Nickel Ni Aluminum Al

Organizing the elements Find the element, identified by the atomic number, complete the information: Atomic Number Name Symbol Atomic mass p+ and e- n 9 12 79 17 53

Organizing the elements Find the element, identified by the atomic number, complete the information: Atomic Number Name Symbol Atomic mass p+ and e- n 9 Fluorine F 19 10 12 Magnesium Mg 24 79 Gold Au 197 118 17 Chlorine Cl 35 18 53 Iodine I 127 74

Organizing the elements Find your name using the element’s symbols Example: CASTRO C – arbon As – Arsenic Tr - ________ O - Oxygen

Organizing the elements An element’s properties can be predicted from their location in the Periodic Table. Period – rows - Are 7 Group or family – column – Are 18 – Each of them have different name and properties. Find the name of the element using the period and group: Period Group Name 3 14 2 17 5 18 4 8

Lesson 3 Pages 88 – 95 Metals

Metals Are the majority of elements. Properties: Luster – shiny Malleability – material is one that can be hammered or rolled into flat sheets or other shapes. Ductile – material is one that can be pulled out, or drawn into long wires. Thermal conductivity – transfer heat. Electrical conductivity – carry electric current.

Metals 6. Reactivity – react with other substance by loosing electrons to other atoms. 7. Corrosion – deterioration due to chemical reaction in the environment.

Metal Classification Alkali Metals (metales alcalinos) Group 1 Most reactive. They are never found as uncombined elements in nature. Always are in compound. Some of them are so soft you can cut them with a plastic knife. Low densities and melting point.

Metal Classification Alkaline Earth metals (metales alcalinotérreos) Group 2 Harder and denser. Melt at high temperature than alkaline metals. Very reactive, but not as the alkaline. Never found uncombined in nature.

Metal Classification Transition metals Groups 3 to 12 Most are hard and shiny solids. Mercury is liquid at temperature room. Except Mercury, they have high melting point and densities. Good conductors of heat and electric current. Very malleable. Are less reactive than the groups 1 and 2.

Metal Classification Metals in mixed groups Only some of the elements on groups 13 through 17 are metals. They are: Al, Ga, In, Sn, Tl, Pb, Bi, and Po. Lanthanides and Actinides (Lantánidos y Actínidos) Top row after the main part of the PT.- Lanthanides Below the Lanthanides – Actinides Not found in nature but are artificially in laboratories.

Metal Classification Transuranium Elements (elmentos transuránicos) Elements follow uranium (U). These elements are made or synthesized, when nuclear particles are forced to crash into one another. Elements with atomic number greater than 111 do not yet have permanent names or symbols. In the future, scientists around the world will agree on permanent names and symbols for these elements.

Metals Let made some excises

Nonmetals and metalloids Lesson 4 Pages 96 - 105 Nonmetals and metalloids

Nonmetals and metalloids Elements that lacks most of the properties of a metal. Except for H, the non metals are found on the right side of the PT. Properties: Poor conductors of electric current and heat. Solid nonmetals are dull and brittle. Lower densities that metals. Most are gases at room temperature.

Nonmetals and metalloids Properties cont. Usually gain or share electrons when they react with other atoms. The families that containing nonmetals include the carbon family, nitrogen family, oxygen family, halogen family, the noble gases and hydrogen. Complete blue table on page 99.

Nonmetals and metalloids Carbon family: Group 14 Only Carbon is nonmetal. It is an important element for life. Nitrogen family: Group 15 Nitrogen and Phosphorus are nonmetals.

Nonmetals and metalloids Oxygen family: Group 16 Oxygen, sulfur and selenium are nonmetals. Halogen Family: Group 17 Fluorine, chlorine, Bromine and iodine are nonmetals. Astatine (At) are rare and properties are unknown. Are vary reactive. Fluorine are the most reactive.

Nonmetals and metalloids Noble gases: Group 18 Do not form compounds because do not gain, lose or share electrons. Nonreactive. Hydrogen: The element with the simplest atom. The properties are very different from those of the other element, so it cannot be grouped in with a family. Is rarely found on earth as a pure element. It found combined with oxygen as water.

Nonmetals and metalloids Are between metals and nonmetals. They have some properties of metals and some form nonmetals. Are solids at room temperature. Brittle, hard and somewhat reactive. Most common is Silicon. Is in sand. The conductivy of electric current , depend on temperature, exposure to light or presence of impurities. Some of them are semiconductors.

Practice First find the name and then classify the following elements in metals, nonmetals and metalloids: 1. Si 2.Rh 3. Br 4. Eu 5. Co 6. F 7. Cs 8. Pb 9.Sb 10. Ag

Review and assessment Pages 115 -116 Fun Practice Perform Alien Periodic table on pages 104 - 105 Period Table Exercise – See teacher for instructions Review and assessment Pages 115 -116

END Any similarity?