GENCHEM - WK2

• Atoms are the simplest and smallest particle composed of protons, electrons, and neutrons.
• The number of protons in the nucleus of an atom is equal to its atomic number.
• Normally, the number of protons equals the number of electrons.
• A proton is a positively charged particle inside the nucleus.
• A neutron is a neutral particle also inside the nucleus.
• An electron is a negatively charged particle that orbits the nucleus.
• Elements are substances that cannot be broken down any further by chemical means.
• The Periodic Table is the arrangement of these elements by increasing atomic number and similar properties.
• Dmitri Mendeleev is known as the Father of the Periodic Table.
• Mendeleev arranged the elements by increasing atomic mass and by the way they reacted.
• Mendeleev wrote each element’s name and properties on a separate card and tried to find a pattern in the properties of the elements that could be used to classify and keep information about them organized in a logical manner.
• The current Periodic Table arranges elements by increasing atomic number.
• The horizontal rows on the Periodic Table are called periods and are labeled from 1 to 7.
• The vertical columns on the Periodic Table are called groups or families and are labeled from 1 to 18.
• Groups on the Periodic Table have similar properties because they have the same number of valence electrons.
• Metals, non-metals, and metalloids are the major categories of elements.
• Metals are lustrous, malleable, and are good conductors of heat and electricity.
• Lustrous means shiny or reflective of light.
• Alkaline Earth Metals are elements in Group 2 and are reactive metals that are always combined with non-metals in nature.
• Carbon Family elements are in Group 14 and contain elements important to life and computers.
• Electronegativity is a measure of the ability of an atom in a chemical compound to attract electrons and tends to increase across a period, as radius decreases, and as radius increases.
• Metalloids are elements that share some, but not all the properties of metals.
• Noble Gases elements are in Group 18 and are very unreactive gases used in lighted neon signs.
• Ionization Energy is the energy required to remove an electron from an atom.
• Being a good conductor means being able to allow electricity and heat to flow through.
• The Periodic Trends include Radius, Ionization Energy, Electronegativity, Ionic Radii, and Halogen Formation Energy.
• Malleable means capable of being shaped.
• Radius tends to increase across a period, decrease down a group, and each row on the periodic table adds a “shell” or energy level to the atom.
• Metals are lustrous, malleable, and good conductors.
• Elements Used Everyday can be any elements you use every day.
• Alkali Metals are elements in Group 1 (not including Hydrogen) and are very reactive metals that always combine with something else in nature.
• Rare Earth Elements, also known as the thirty rare earth elements, are composed of the lanthanide and actinide series and are mostly synthetic or man-made.
• Boron Family elements are in Group 13 and Boron has properties of both metals and nonmetals.
• Transition Metals are elements in Groups 3-12 and are less reactive, harder metals that include metals used in jewelry, money and construction.
• Ionic Radii are smaller for cations and larger for anions.
• Oxygen Family or Chalcogens elements are in Group 16 and Oxygen is necessary for respiration.
• Halogens elements are in Group 17 and are very reactive, diatomic non-metals that are always found combined with other elements in nature.
• Non-metals are elements that do not share the properties of metals.
• Nitrogen Family elements are in Group 15 and Nitrogen makes up more than ¾ of our atmosphere.