chemistry

• Everything in this world is made up of elements, and we

  have discovered 118 of them
• Periodic table:

  an organizational table of elements ARRANGED

  according to its atomic number.
• periods horizontal

  groups - vertical
• the data that can be seen in an element's tile: atomic number, mass, element's name and symbol
• Mass = Neutrons + Protons
• Number = Protons = Electrons
• An atom is the basic unit of matter with protons, electrons, and neutrons. It is the smallest particle that has unique properties.
• Element : A specific type of atom that has unique number of protons, electrons, and neutrons.
• Which parts of the atom are

  the ones kept in the center?

  Protons and Neutrons
• Which part of the atom are

  the ones orbiting in outer

  layers?

  Electrons
• These noble gases do not seem to mingle or react with any element at all, unlike all elements that do not exist solo. They termed these elements as INERT or STABLE.
• Chemists have this widely accepted theory/rule

  that ELEMENTS PREFER TO HAVE 8 ELECTRONS

  in their valence (outer) shell to make themselves

  STABLE.

  They call this as the OCTET RULE.
• Elements want to copy the structure of the Noble

  gases, so they want to acquire their valence electrons.
• Hydrogen is an exception of the Octet Rule. It only

  needs two (2) valence electrons to be stable.
• Lewis Dot Structure:

  A visual model showing an element’s valence electrons. It will later help in visualizing chemical bond and their types.
• Elements can GIVE or TAKE electrons, with the first element losing its valence electrons, and the other completing its valence electrons.
• They also have elements that have 3 or less valence electrons, and

  they donate them instead to become stable.
• Metals are solid, good conductors of electricity and heat, and are

  malleable (made into sheets) and ductile (made into wires).
• Non metals are elements with properties OPPOSITE of METALS, usually liquid/gas, and have 4 or more valence electrons
• They are receivers of valence electrons to become

  stable
• examples of nonmetals: hydrogen, helium, oxygen
• metals examples: aluminium, gold, zinc
• there are 17 nonmetals
• Metalloids can have properties of both metals and nonmetals , which vary from element to element.
• Metalloids are found on the MIDDLE of metals and non metals of the periodic table, and are making a staircase figure.
• examples of metalloids: boron, silicon
• Chemical Bond:

  Attractive force that holds atoms of elements together in a compound
• Ionic Bonding :

  • Refers to the TRANSFER (give & take) of valence

  electrons of METAL + NON METAL elements.
• Products of ionic bonding are called ionic compounds
• Ionic compounds are usually solid, have high melting points, and conductors of electricity when dissolved in water.
• Losing electrons makes the metal become

  positively charged and the non-metal becomes negatively charged
• Because of opposite charges, they become close to each other and form a compound
• Ionic compounds are strong and crystal-structured
• example of ionic compound: NaCl (Sodium Chloride)
• Covalent Bonding :

  • Refers to the SHARING of valence electrons of

  two or more NON METAL elements.
• Products of covalent bonding are called covalent molecules.
• Covalent compounds are usually liquid/gaseous, have low melting points, and insulators of electricity
• ionic compouds are stronger than covalent molecules
• When metals are packed together, they form a shape

  called “Lattice”, appearing as if they are ionic bonds.
• When metals stick together, their electrons stick together, too.