Chapters 7&8 Gauge Sheet 7.1- Ions To find the number of valence electrons in an atom of a representative element‚ simply look at its group number. Atoms of metals tend to lose their valence electrons‚ leaving a complete octet in the next-lowest energy level. Atoms of some non-metals tend to gain electrons or to share with another non-metal to achieve a complete octet. The gain of negatively charged electrons by a neutral atom produces an anion. 7.2- Ionic Bonds and Ionic Compounds Although
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atom‚ a metal makes a contribution of an electron and becomes a optimistic ion‚ and when another‚ a nonmetal received an electron and becomes pessimistic ion. Metal donate electrons and non-metals receives electrons. For example is Na is positive and CL is negative. The covalent bonds share the electrons and they are normally nonpolar. The covalent bonding does not donate or gain electrons such as CH4. The ionic compounds tend to have eight electrons to keep in the highest energy level. The
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incorporating in the pore. In addition‚ when we are speaking about electronic conductivity‚ it should be mentioned that electrons do not have an absolute monopoly on electrical conduction in solids. In literature still possible to meet a great uncertainty as to whether typical measurements allow researcher to conclude that conduction in a given m is due predominately to ions or to electrons. Many researchers have assumed that some of the MOFS can be treated as wide band gap semiconductors but other scientists
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Chemistry Review sheet: Unit 1- Lesson 1‚ 2 *Key notes to keep in mind* ü Metals have a high low ionization energy ü Non-metals have a high electron affinity · Atom: The basic unity of an element which still retains the elements properties · Atomic number: the unique number of protons in the nucleus of a particular element · Isotope: Atoms of the same element which contain a different number of neutrons · Periodic law: The chemical
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Lewis Structure Review How To Write Lewis Structures 1. Determine the total number of valence electrons from all of the atoms in the molecule or ion. • Add one electron for each unit of negative charge. • Subtract one electron for each positive charge. 2. Write the correct skeletal structure. • For molecules of the formula ABn‚ place the least electronegative element in the center‚ and the more electronegative elements in the terminal positions. • H is always a terminal atom‚ and NEVER a central
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Protons or Electrons Atomic mass equals the number of Protons + Neutrons Using the periodic table‚ fill in the chart for each Atom (Round the atomic mass to the nearest whole number). 2. Carbon (C) Atomic # = ____6__Atomic Mass = _ 12 _ # of Protons = ____6____# of Neutrons = ___6_____# of Electrons = ___6_____ # of Electrons in the valence shell? __4___ 3. Oxygen (O) Atomic # = ___8___Atomic Mass = ___16____ # of Protons = ____8____# of Neutrons = ____8____# of Electrons = ___8_____
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Sharing Electrons Example~ A hydrogen atom has one electron. If it had two electrons‚ it would have the same electron configuration as a helium atom. Two hydrogen atoms can achieve a stable electron configuration by sharing their electrons and forming a Covalent bond. A covalent bond is a chemical bond in which two atoms share a pair of valence electrons. When two atoms shair one pair of electrons‚ the bond is called a singe bond. Molecules of Elements Two hydrogen atoms bonded together
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together to become a stable‚ new substance called a compound. -the number of valence electrons determines if an atom will form a chemical bond. -metals tend to give up electrons to other atoms. -nonmetals tend to take electrons from other atoms. -noble gases will not form a chemical bond because these atoms already have a full outer shell of energy. Ionization: the process of gaining or losing electrons to become an ion. -ion: atom that has a net positive or negative charge. -anion
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the two atoms Valence electron – the outer most shell electrons There are three types of chemical bonding i. Ionic bond: ________________________________________ ii. Covalent bond: _____________________________________ iii. Dative Covalent bond: _______________________________ 1.1.1 LEWIS DOT SYMBOL A shorthand to represent the valence electron of an atom. The element symbol surrounded by dots that represent the valence electrons. The Lewis structures
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ionic bonding Molecule (nonmetal +nonmetal): covalent bonding 3.1 Metallic Bonding 1) Definition The electrostatic attraction between a lattice if positive ions and delocalized electrons. 2) The strength of metallic bonding (depend on) Delocalized electrons (=valence electrons=Group number) More valence electrons‚ stronger metallic bonding Ionic radii (=distance between nucleus and e-) Greater ionic radius‚ farther distance between nucleus and Ve-‚ stronger the metallic bonding 3) Physical
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