Periodical Test Preparation

• Malleability


  The property of a material to be easily hammered or pressed into shapes without breaking
• Flammability


  The tendency of a material to ignite and burn when exposed to fire or heat
• Ancient Greek philosophers Leucippus and Democritus


  Believed that nature consisted of two things, atoms and the void that surrounds them
• Evaporation 


  The substance changes from liquid to gas
• Valence Electrons


  The outmost electrons.
• John Dalton


  An English chemist who started the use of symbols in representing the atoms of different elements in 1803
• Johannes Wolfgang Dobereiner


  A German Chemist, studied three elements and noticed similarities among the properties of metals such as CA, Ba, and Sr in 1817.

  He continued to study another group of three elements called TRIADS. 
• Dmitri Ivanovich Mendeleev


  A Russian Chemist and Inventor

  Best remembered for formulating the Periodic Law and creating a far sighted version of the Periodic Table of Elements.
• The periodic table is organized by increasing atomic number. The first row contains only one element, Hydrogen (H). Each subsequent row has eight columns with different chemical properties. These rows are referred to as periods.
• Non-metals are not good conductors of heat and electricity. Non-metals do not reflect light well. Most non-metals exist at room temperature as solids. Some examples of non-metals include carbon (C), nitrogen (N), oxygen (O), sulfur (S), chlorine (Cl), iodine (I), fluorine (F), phosphorus (P), selenium (Se), tellurium (Te), helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), radon (Rn), hydrogen (H)
• Increasing atomic mass means that there will be more protons than neutrons in an atom's nucleus. This leads to greater attraction between the positively charged protons and negatively charged electrons, resulting in stronger bonds between atoms.
• Henry Moseley proposed that the recurring pattern in the properties of the elements are better related to their atomic numbers than to their atomic masses
• Dry ice sublimates at room temperature. This means that dry ice changes from solid to gas
• What happens to the particles of ice as it changes to water? Particles move and increase their intermolecular space
• Rutherford’s alpha scattering experiment suggested that atoms are mostly empty space
• Water at 25ºC is heated and changes to gas at 100ºC. What happens to the water molecules? Water molecules move farther apart
• The figure below shows the changes in the phase of water. What process does Z represent? Evaporation
• Proton


  The subtomic particle that determines the identity of an element
• The nucleus is made of protons and neutrons and has a positive charge
• Energy absorption during evaporation or vaporization

  It breaks the water molecules away from other water molecules
• Determining the number of neutrons in a neutral atom

  Subtract its atomic number from its mass number
• Rutherford's alpha scattering experiment suggested that atoms are mostly empty space
• Mass number of an element with 19 protons, 19 electrons, and 20 neutrons is 39
• Oxygen has an atomic number of 8, meaning an oxygen atom has 8 protons in its nucleus
• Isotopes


  Have the same number of protons but different numbers of electrons
• Elements are grouped according to their chemical properties

  Predicted by their location in the periodic table
• Metalliods

  • Found along a zigzag line in a periodic table
• Noble Gases


  • Neon
  • Argon
• From Be to Ra on the table

  Metallic properties of the elements increase
• Both liquids and gases can flow
• Gas changing directly into a solid

  Gas releases heat, process is called deposition
• Water heating and changing to gas

  Water molecules move apart
• An electron has less mass than either a proton or neutron
• For ion X with 20 protons and 22 neutrons and an overall charge of +2, the mass number is 42 and the amount of electrons is 18
• The development of the first periodic table similiar to the one we are using today is credited to Dmitri Mendeleev
• Henry Moseley proposed that the recurring pattern in the properties of the elements are better related to their atomic number than their atomic mass.