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Chapter 7.1 Ions
Transcript of Chapter 7.1 Ions
Chemistry and you
Formation of Anions
When atoms of the halogens gain an electron they are called halide ions.
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Chapter 7.1 Ions
Assess Prior Knowledge
How does the charge of an atom change if it gains or loses and electron?
It will have a positive charge if it loses an electron or a negative charge if it gains an electron.
What would happen if the charged atoms were near each other?
Atoms with opposite charges would be atracted to each other
What is another example of a metal that develops a film of a different color on the surface when exposed to air?
How are the stryctures of gypsum and selenite different?
Gypsum is imperfect and selenite forms perfect cystals.
How are the particles organized in a crystalline solid?
In an orderly repeating fashion.
What is formed when atoms gain or lose electrons?
Valence electrons: the electrons in the highest occupied energy level of an element's atoms.
*To find the number of valence electrons in an atom of a representative element, simply look at its group number.
Electron Dot structures: also called Lewis Valence electron dot structures, are diagrams that express the arrangement of valence electrons in the atoms of an element as dots.
*The octet rule: states that in forming compounds, atoms tend to achieve the electron configuration of noble gases. An octet is a set of 8. All elements want to have 8 electrons in their valence shell like the noble gases, except for Hydrogen which only wants 2 like Helium.
*A positively charged ion, or a cation, is produced when an atom loses 1 or more valence electrons.
Na becomes Na+ because it will lose an electron.
Mg will lose 2 electrons, therefore it becomes Mg2+
Al will lose 3 electrons and become Al3+.
Almost all cations are metals.
*An anion is produced when an atom gains one or more valence electrons.
Cl becomes Cl- when it gains an electron.
O becomes o2+ because i will gain 2 electrons.
N will become N3- because it will gain 3 electrons.
All halogens have 7 valence electrons and need to gain only 1 electron to reach noble gas electron configuration.
All halides have a charge of -1