Chapter 8.1: Electrons and Energy Levels


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Grade 8 Integrated Science Chapter 8 Lesson 1 on electrons and energy levels, as well as understanding the periodic tables.

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Chapter 8.1: Electrons and Energy Levels

  1. 1. Chapter 8.1: Electrons and Energy Levels - p266-272 – page1 Vocabulary  Chemical bond (268) – a force that holds two or more atoms together  Valence Electron (270) – an outermost electron of an atom that participates in chemical bonding  Electron Dot Diagram (271) – a model that represents valence electrons in an atom as dots around the element’s chemical symbol Periodic Table of Elements  Shows us: o Elements o __________________________ o State of matter at room temperature o Atomic (average) Mass  Periods and Groups o ___________________ = Rows o Groups = Columns o Lists elements in order of atomic number o Atomic number increases as you move from ________________ to _________________ o Elements in each group have similar chemical properties and react with other elements in similar ways  Metals, Nonmetals, and Metalloids o Metals  Often shiny  Good __________________ of electricity and thermal energy  Easily pulled into wires and hammered into sheets o Metalloids  Have properties in common with both metals and ________________  Often used as semiconductors in electronic devices o Nonmetals  Poor conductors of thermal energy and electricity  Most are _____________________at room temperature  Solid form tends to be brittle Atoms Bonds  Compounds o Pure elements are _____________________to find o Atoms of different ____________________chemically combine and form compounds. o Compounds make up all living and nonliving things  Bonding o Chemical ________________ hold together different elements in chemical compounds o A chemical bond is a force that holds two or more atoms together
  2. 2. Chapter 8.1: Electrons and Energy Levels - p266-272 – page2  Electron Number and Arrangement o The exact ___________________ of electrons in an atom cannot be determined. o Electrons are in constant _________________around the nucleus o However, each electron is usually in a certain area of space around the nucleus o Some are in areas close to the nucleus, and some are in areas farther away  Electrons and Energy o Different electrons in an atom have different amounts of_____________. o An electron moves around the nucleus at a _________________that corresponds to its amount of energy o Areas of space in which electrons move around the nucleus are called energy levels o Electrons closet to the nucleus have the least amount of energy  They are at the _____________ lowest energy level  Only _____________ electrons can be in the lowest energy level  Electrons and Bonding o Negatively charged electrons have an attraction to the _________________ charged nucleus of an atom (like a magnet) o The electrons in the energy levels closest to the nucleus of the same atom have a __________________attraction to that nucleus o Electrons farther from that nucleus are ______________________ attracted to it. o These outermost electrons can easily be attracted to the nucleus of the other atoms o This __________________ between the positive nucleus of one atom and the negative electrons of another is what causes a chemical bond.  Valence Electrons o Electrons farthest from their nucleus are easily attracted to the nuclei of ________________ atoms. o These outermost electrons are the only electrons that can form chemical bonds  This is because these electrons are exposed to the nuclei of other atoms o A __________________electron is an outermost electron of an atom that participated in chemical bonding. o Valence electrons have the most ____________________of all electrons in an atom. o The number of valence electrons in each atom of an element can help determine the type and the number of _______________ it can form. o The periodic table can tell you how many valence electrons an atom has.
  3. 3. Chapter 8.1: Electrons and Energy Levels - p266-272 – page3  Except for Helium, elements in certain groups have the same number of valence electrons o In groups 1,2, 13-18, the number of valence electrons is shown by the ___________ digits of the group. o So, elements in group 18 have __________ valence electrons.  Electron Dot Diagrams o In 1916, an America Chemist named Gilbert Lewis developed the electron dot diagram. o The electron dot diagram is a model that represents __________________electrons in an atom as dots around the element’s chemical symbol o It can help you predict how an atom will ____________ with other atoms o The dots represent the valence electron o Some dots pair up, others do not o The number of _________________dots is often the number of bonds an atom can form o See Figure 5, pg 271 - Draw the Lewis Dot Structure for the elements in the chart Na He F Al  Valence Electrons o Remember that each element in a _________________ has the same number of valence electrons. o SO, every element in a group has the same number of _________________ in its electron dot diagram o Atoms with 8 valence electrons do not easily react with other atoms  They are chemically stable o Atoms that have 1-7 valence electrons are reactive of chemically unstable  They easily bond with other atoms and form chemically ____________ compounds o Atoms of H and He have only one energy level  These atoms are chemically stable with _____________ valence electrons  Noble Gases o Elements in Group __________________ are called noble gases o With the exception of He, noble gases have ______valence electrons and are chemically
  4. 4. Chapter 8.1: Electrons and Energy Levels - p266-272 – page4 stable. o Chemically stable atoms do not easily____________________________, or form bonds, with other atoms  Stable and Unstable Atoms o Atoms with unpaired dots in their electron dot diagram are reactive, or chemically unstable. o For example, N has 5 valence electrons are ______________ of them are unpaired. o It is reactive and will become more stable by forming chemical bonds with other atoms o When an atom forms a bond, it__________________, loses, or shares valence electrons with other atoms. o By forming bonds, atoms become more chemically stable