U NIT 6 I ONIC B ONDING & N AMING Chapter 7.1 Ions & 7.2a Ionic Bonds and Ionic Compounds V ALENCE E LECTRONS What is a valence electron? V ALENCE E LECTRONS What is a valence electron? electron in the highest occupied energy level determines the chemical properties of an element V ALENCE E LECTRONS What is a valence electron? electron in the highest occupied energy level determines the chemical properties of an element How do you find the number of valence electrons in an atom of a representative element? V ALENCE E LECTRONS What is a valence electron? electron in the highest occupied energy level determines the chemical properties of an element How do you find the number of valence electrons in an atom of a representative element? Group # Represented by Electron Dot Structures E LECTRON D OT D IAGRAM /S TRUCTURE Element symbol represents: Nucleus AND All inner core electrons Dots represent: Valence electrons F E LECTRON D OT S TRUCTURES S TABLE E LECTRON C ONFIGURATIONS When is an atom unlikely to react? S TABLE E LECTRON C ONFIGURATIONS When is an atom unlikely to react? Stable Highest occupied energy level is full S TABLE E LECTRON C ONFIGURATIONS When is an atom unlikely to react? Stable Highest occupied energy level is full Noble Gases unreactive S TABLE E LECTRON C ONFIGURATIONS When is an atom unlikely to react? Stable Highest occupied energy level is full Noble Gases unreactive Gilbert Lewis Octet Rule In forming compounds, atoms tend to achieve the electron configuration of a noble gas. S TABLE E LECTRON C ONFIGURATIONS Octet Rule Atoms will gain or lose valence electrons in order to fill or empty the highest occupied energy level (which ever is easiest) 8 Full 0 Empty F ORMATION OF I ONS When an atom gains or loses an electron(s) atom is no longer neutral. # of Protons NO LONGER EQUAL # of electrons Creates an ION = atom (or group of atoms) with positive ( +) or negative ( -) net electric charge. Cations Anions F ORMATION OF I ONS CATION = Ion with a positive charge (loses valence electrons) F ORMATION OF I ONS CATION = Ion with a positive charge (loses valence electrons) F ORMATION OF C ATIONS 7.1 F ORMATION OF C ATIONS Group 1A charge of 1+ Group 2A charge of F ORMATION OF I ONS ANION = Ion with a negative (-) charge (gains valence electrons) F ORMATION OF I ONS ANION = Ion with a negative (-) charge (gains valence electrons) F ORMATION OF A NIONS 7.1 I ONIC B ONDING Where are the electrons going/coming from? I ONIC B ONDING Chemical bond = force that holds atoms or ions together as a unit. Ionic Bonding where does the force come from? I ONIC B ONDING Chemical bond = force that holds atoms or ions together as a unit. Ionic Bonding where does the force come from? Opposite charges I ONIC B ONDING Chemical bond = force that holds atoms or ions together as a unit. Ionic Bonding where does the force come from? Opposite charges What is the electrical charge of an ionic compound? I ONIC B ONDING Chemical bond = force that holds atoms or ions together as a unit. Ionic Bonding where does the force come from? Opposite charges What is the electrical charge of an ionic compound? ionic compounds are electrically neutral I ONIC B ONDING Chemical bond = force that holds atoms or ions together as a unit. Ionic Bonding where does the force come from? Opposite charges What is the electrical charge of an ionic compound? ionic compounds are electrically neutral Ionic bond Force that holds cations and anions together and which involves the transfer of electrons. Bond occurs between a metal and a nonmetal P ROPERTIES OF I ONIC C OMPOUNDS High melting point sodium chloride melts ~800C Solid - poor conductor of electric current Liquid (melted/dissolved) - good conductor of electric current. Free movement of ions Brittle F ORMATION OF I ONS & B ONDING Sodium reacts with chlorine F ORMATION OF I ONS & B ONDING Sodium reacts with chlorine F ORMATION OF I ONS & B ONDING Sodium reacts with chlorine electron transferred from sodium to chlorine F ORMATION OF I ONS & B ONDING Sodium reacts with chlorine electron transferred from sodium to chlorine F ORMATION OF I ONS & B ONDING Sodium reacts with chlorine electron transferred from sodium to chlorine Each atom ends up more stable F ORMATION OF I ONS & B ONDING A chemical formula shows the kinds and numbers of atoms. F ORMATION OF I ONS & B ONDING A chemical formula shows the kinds and numbers of atoms. NaCl F ORMATION OF I ONS & B ONDING A chemical formula shows the kinds and numbers of atoms. NaCl A formula unit is the lowest whole-number ratio of ions in an ionic compound. F ORMATION OF I ONS & B ONDING A chemical formula shows the kinds and numbers of atoms. NaCl A formula unit is the lowest whole-number ratio of ions in an ionic compound. 1:1 NaCl I ONIC B ONDING What is the chemical formula for magnesium chloride? Mg and Cl K + F B E + S N A + O A L + S