1 Unit 4: Atomic Structure and the Periodic Table Vocabulary: Atom Proton Neutron Electron Nucleus Term Definition Sub-atomic particle with positive (+) charge; located in nucleus of atom; determines identity of element Sub-atomic particle with negative charge; much smaller than protons and neutrons Valence Electron Atomic Number Electron found in outermost shell of an atom; determines atoms chemical properties Mass number Atomic Mass Weighted average of masses of isotopes of each atom Isotope Atom with same # of protons as other atoms of that element, but different # of neutrons Ion Bohr Model Model used to visualize atomic structure Lewis Dot Structure ph scale Acid Base Gravitational Force Compound which increases hydroxide ions (OH-) when dissolved in H2O Attraction of objects due to their masses and distance; weakest force Electromagnetic Force Force Weak Nuclear Force Strong Nuclear Force Holds the atomic nucleus together; Counteracts the electromagnetic force Periodic Table e
2 Group Period Vertical (up and down) column of periodic table; elements in group share chemical properties (same # valence electrons) Metals Non-metals Metalloids usually gases or brittle solids at room temp; are poor conductors; to right of stair step Have characteristics of metals and non-metals; make up stair step Section 1: Atomic Structure Key Ideas Know the structure of atoms Explain how sub-atomic particles are different in terms of mass, electrical charges, and location in the atom Understand Hydrogen ion concentration in acids and bases, and how the ph scale measures acids and bases Vocab: Atom Valence Electron Ion Proton Atomic Number Bohr Model Neutron Mass Number Lewis Dot Electron Atomic Mass ph scale Nucleus Isotope Acid Base Watch video and answer: How small are atoms? If they are so small, how do we know they exist? History of the Atom: For thousands of years, many scientists have been trying to figure out what makes up all matter? Of course, its atoms. But what are they made of? What do they look like? How do they work? After many scientists contributions, and many experiments, we now have a, that is supported by all previous evidence
3 Progression of the Atomic model and History of the Atom Timeline: Scientist Picture of Model Name Discovery Billiard Ball Model Plum Pudding Model The Electron The Proton Bohr Model Electron Cloud Model Can not predict exactly where an electron will be; electrons have erratic behavior The Neutron What are the building blocks of matter? What is matter? What are atoms made of? Smallest possible unit into which matter can be divided, while still maintaining its properties. Made up of: _ _ _ The solar system is commonly used as an analogy to describe the structure of an atom Atoms are so small that: It would take a stack of about 50,000 aluminum atoms to equal the thickness of a sheet of aluminum foil from your kitchen. If you could enlarge a penny until it was as wide as the US, each of its atoms would be only about 3 cm in diameter about the size of a ping-pong ball A human hair is about 1 million carbon atoms wide. A typical human cell contains roughly 1 trillion atoms. A speck of dust might contain 3x10 12 (3 trillion) atoms.
4 It would take you around 500 years to count the number of atoms in a grain of salt. Protons: Help identify the atom (could be considered an atom s DNA) Neutrons: Mass number protons = neutrons Electrons: Negatively charged particles Found outside the nucleus of the atom, in the electron orbits/levels; Each orbit/level can hold a maximum number of electrons ( 1 st = 2, 2 nd = 8, 3 rd = 8 or 18, etc ) Move so rapidly around the nucleus that they create an electron cloud Mass is insignificant when compared to protons and neutrons (smallest) = to number of protons, in a neutral atom Involved in the formation of chemical bonds Valence Electrons: Electrons that can be gained, lost or shared in How many valence electrons does this atom have? What element is this atom?
5 Bohr Model: Even though this model is not correct, we use it to easily visualize what is happening with protons, neutrons and electrons. How do we know that this model is Nitrogen? Lewis Dot Structure: Lewis Dot Structure shows the number of valence electrons for atoms. How many valence electrons does this atom of Nitrogen have? How many total electrons does it have? Draw the Bohr Model of each Atom: Hydrogen: Oxygen: Sodium: Sub-Atomic Particle Weight Comparison: Neutron=1.6749286x10-27 kg Proton=1.6726231x10-27 kg Electron = 9.1093897 x10-31 kg Which particle is smallest? Which two particles are very similar in size (mass)?
6 Atomic Number: Same as What is the atomic number of this atom? Mass Number: Draw this an easier way: _ + Tells us the number of protons and neutrons in an atom s nucleus Expressed in Atomic Mass Units (amu) Each proton or neutron has a mass of 1 amu What is the mass number of the above atom? Why don t we care about the number of electrons? What are the atomic and mass numbers (amu) for the following atoms? Mass Atomic Atoms Protons Neutrons Electrons Number Number Bohr Model Carbon 6 6 6 Beryllium 4 5 4 Oxygen 8 8 8 Lithium 3 4 3
7 Sodium 11 12 11 Average Atomic Mass: The weighted average of the masses of all the naturally occurring The average considers the percent abundance of each isotope in nature Found on the periodic table of elements Ion: _ If I gain electrons, I get a negative charge If I lose electrons I get a positive charge Build the following ions, and determine their atomic and mass numbers. Mass Atomic Atoms Protons Neutrons Electrons Number Number Bohr Model Carbon (C 3- ) 6 6 9 Hydrogen (H 1+ ) 1 0 0 Oxygen (O 2- ) 8 8 10 Lithium (Li 3+ ) 3 4 0 Sodium (Na 1- ) 11 12 12 ***Be aware that the atomic and mass numbers are not impacted by the loss or gain of electrons.
8 Acids and Bases and the ph Scale: (Draw and label the ph Scale) ph Scale : Acids and Bases: Acid: Base (alkaline): ****ph of 7 is neutral; neither an acid or a base Section 2: Forces in the Atom: Key Ideas: Understand the magnitude and range of the four fundamental forces Recognize the effect of each force on the structure of matter Vocab: Gravitational Force - Strong Nuclear Force Electromagnetic Force - Weak Nuclear Force
9 Forces Gravitational Electromagnetic Strong Nuclear Weak Nuclear _ The amount of gravity between objects depends on their masses and the distance between them This force plays a key role in the possible change of sub-atomic particles. For example, a neutron can change into a proton(+) and an electron(-) The force responsible for radioactive decay. Radioactive decay process in which the nucleus of a radioactive (unstable) atom releases nuclear radiation. Section 3: The Periodic Table Key Ideas Relate the properties of atoms and their position in the periodic table to the arrangement of their electrons Vocab Periodic Table - Metal Group - Non-Metal Period - Metalloid What is the Periodic Table of the Elements? Resource Information: Nova Interactive Periodic Table First Organizers: Dmitri Mendeleev (late 1800 s), Russian chemist Organizes first periodic table based on atomic mass, but some elements are out of order Henry G.J. Moseley (1913), British chemist Arranged elements by atomic number, which is what we use today Student of Rutherford
10 How is the Periodic Table Actually Organized? Groups: Example: Every element in group 1, has 1 electron in its outer shell, every element in group 2, has 2 electrons in its outer shell, and so on (excluding transition metals) ****Remember: Valence Electrons are electrons in the last shell or energy level of an atom Important because: Determine an elements ability to bond with another element Chemical properties depend almost entirely on the configuration of the outer electron shell (reactivity, flammability, etc.) Periods: Each row in a period ends when an outer energy level is filled Example: Every element in the top row has 1 orbital for its electrons, 2 nd row has two orbitals and so on
11 Categories of elements in the periodic table: Alkali Alkaline Earth Transition Metals Basic metal Semi metal Non-Metal Halogens Noble Gas Lanthanide (rare-earth) - radioactive Actinides (rare-earth) - radioactive 3 Main Categories (you have to know!!!!) Metals: All but Mercury are solid at room temp Alkali Metals (Group 1) are the most reactive of all metals; don t occur in nature in their element form Alkaline Earth Metals (Group 2) shiny, ductile and malleable; combine readily with other elements Transition Metals (Group 3 12) most familiar metals because they often occur in nature uncombined Inner Transition Metals Lanthanide Series elements with atomic # 58-71 Actinide Series elements with atomic # 90-103 Non-Metals: Elements that are: are poor conductors Noble gases (Group 18) exist as isolated atoms. They are all stable because the outer energy level is filled.
12 Metalloids: Have metallic and non-metallic properties (share characteristics with metals and non-metals) Part of the mixed groups (groups 13, 14, 15, 16 and 17) which contain metals, non-metals and metalloids How to read the periodic table: (KNOW THIS) Practice: Choose 3 elements and draw the box from the periodic table and the Bohr model for each. 1. 2. 3.