Chemistry

Chemistry

1. Atomic Theory & Bonding

   • Bohr diagrams show the arrangement of protons, neutron, and electrons in atoms and also in ions.
   • Ions are formed from atoms that have gained or lost electrons.
   • Compounds can be ionic or covalent.
   • Lewis diagrams show the arrangement of bonds within compounds.
   • An atom is the smallest particle of an element that has the properties of that element.
   • An element is a pure substance that cannot be chemically broken down into simpler substances.
   • A compound is a pure substance that is made up of two or more different elements that have been combined in a specific way.
   • An atom includes smaller particles called protons, neutrons, and electrons. Protons are subatomic particles that have a 1+ (positive) charge. Neutrons are subatomic particles that do not have an electric charge. Electrons are subatomic particles that have a 1− (negative) electric charge.
   • Rows of elements (across) are called periods.
   • Columns of elements (down) are called chemical families or groups. • All elements in a family have similar properties and bond with other elements in similar ways. • Group 1 = alkali metals Group 2 = alkaline earth metals Group 17 = halogens Group 18 = noble gases
   • Metals are on the left side of the table, non-metals are on the right side, and the metalloids form a “staircase” toward the right side.
   • Atoms gain and lose electrons to form bonds. • When atoms gain or lose electrons, they become electrically charged particles called ions.
   • Metals lose electrons and become positive ions. • Some metals are multivalent, which means they lose electrons in different ways
   • Non-metals gain electrons and become negative ions.
   • A Bohr diagram is a model of the atom that describes the arrangement of an element’s subatomic particles: neutrons and protons in the nucleus and electrons in electron shells .
   • Patterns of electron arrangements in periods: • The period number equals the number of shells in the atom. • The valence electrons are in the same shell for all elements in a period.
   • Patterns of electron arrangements in groups: • Except for the transition elements (Groups 3–12), the last digit of the group number equals the number of electrons in the valence shell.
   • Electrons can exist singly as unpaired electrons, or they can be in pairs, called paired electrons.
   • A compound can be formed when the valence electrons of two atoms interact and form a low-energy bond.
   • A pair of electrons in the valence shell that is not used in bonding is sometimes called a lone pair.
   • In ionic bonding, the bond forms as a result of the attraction between positively charged ions and negatively charged ions.
   • In covalent bonding, the bond forms through the sharing of one or more pairs of electrons. • Covalent bonds form when electrons are shared between two non-metals. • The pair of electrons involved in a covalent bond is sometimes called the bonding pair. • Electrons are not transferred, but their outer shells overlap.
   • A molecule is a group of atoms in which the atoms are bound together by sharing one or more pairs of electrons.
   • In diatomic elements, pairs of electrons are joined by covalent bonds because the two-atom molecules are more stable than the individual atoms.
   • Lewis diagrams represent the atom of an element by showing only the outer valence electrons
   • Lewis diagrams of ionic bonding: • For positive ions, one electron dot is removed from the valence shell for each positive charge. • For negative ions, one electron dot is added to each valence shell for each negative charge of the ion. • Square brackets are placed around each ion to indicate transfer of electrons
   • Lewis diagrams of covalent bonding: • Valence electrons are drawn to show sharing of electrons. • The shared pairs of electrons are usually drawn as a straight line

2. Names & Formulas of Compounds

   • Compounds can be represented with both a name and a chemical formula.
   • • In an ionic compound, the first part of the name indicates the positive ion and the second part indicates the negative ion. • In the formula of an ionic compound, the subscripts indicate the ratio in which the positive ions and negative ions are present together in the compound.
   • The name of an ionic compound always has two parts, one for each type of ion in it.

3. Chemical Equations

4. Acids & Bases

5. Salts

6. Organic Compounds

7. Types of Chemical Reactions

8. Factors Affecting The Rate of Chemical Reactions

9. Atomic Theory, Isotopes, & Radioactive Decay

10. Half-life

11. Nuclear Reactions