Semiconductor c. Insulator • Number of valence electrons is 1-3 with very high conductivity • Number of valence electrons is 4 with intermediate conductivity • Number of valence electrons is 5-8 with very low conductivity Semiconductor Conductors • Has more electrons that are free to move • Supports charge carriers to flow • Support flow of electricity • Has very low resistance allowing easy flow of electron current • Has less than 4 valence electrons – Examples: metals‚ electrolytes
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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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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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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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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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bonds are formed when atoms share electrons‚ one from each atom in a single bond‚ to form electron pairs‚ usually making their outermost shells up to eight electrons by this means. This would make them more stable‚ less reactive and an electronic structure like a noble gas. They are most frequently formed between pairs of non-metallic elements. Non-metallic elements usually have from four to eight electrons in their outermost shells‚ the so-called valency electrons‚ which are used for chemical bonding
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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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Chapter 7 Matching Match each item with the correct statement below. a. halide ion e. valence electron b. octet rule f. coordination number c. ionic bond g. metallic bond d. electron dot structure ____ 1. an electron in the highest occupied energy level of an atom ____ 2. Atoms react so as to acquire the stable electron structure of a noble gas. ____ 3. a depiction of valence electrons around the symbol of an element ____ 4. an anion of chlorine or other halogen ____ 5. the force of attraction
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Transition Metal: element of groups 3-12 * Energy level: a space with definite and fixed energy in which an electron is allowed to move * Orbit: circular/spherical path in which the electron can move around the nucleus * Electron Cloud: the region of an atom in which there is a probability that an electron exists * Quantum Mechanics: theory of the atom in which electrons are described in terms of their energies/probability patterns (model looks like smoke around a circle) * Principal
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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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