Science 9

• The four types of bases found in DNA are adenine (A), thymine (T), cytosine (C), and guanine (G).
• Atom- smallest unit of matter.
• Sub-atomic particles; proton, neutron, electrons
• Proton- positibely charged, can be found in the necleous.
• Neutron- no charge/ neutral, can be found in the necleous.
• Electron- negatively charged particles.
• Sir James Chadwick - discovered neutrons
• Isotopes- have the same number of protons but different number of neutrons.
• Atoms are being held through Chemical Bonds.
• Different types of Chemical Bonds; Ionic Bonds and Covalent Bonds.
• Electronic configuration- shows the distribution of electrons in an atom.
• [S, maximum 2,P maximum 6, D maximum 10, F maximum 14.] Called as energy levels.
• Octet Rule- atoms lose or gain electrons to achieve stability. It needs 8 electrons in order for it to be stable.
• Covalent Bond- sharing of electrons between atoms of both non-metal elements.
• Ionic Bond- transfer electrons between atoms betwern metal and non-metal.
• Polar Covalent Bond- occurs between two atoms having unequal electronegativities. They share of Unidentical atoms.
• Non- Polar Covalent bond- occurs between two atoms having equal electronegativities. Sharing of identical atoms which are non-metals.
• The use of noble gas configuration helps shorten the electronic configuration of an element.
• Lewis Strcuture- a diagram that shows the bonding between atoms of a molecule as well as the lone pair of electrons.
• Ionic Compounds: MgS


  Magnesium Sulfide
• • Anion- non metal, negatively charged ions
• Cation- metal, positively charged ions
• When an atom loses or gains electrons, it becomes ions. And undergoes the process ionization.
• 2 types of ion; cations and anions.
• Polyatomic ions- contains 2 or more elements
• Monatomic ions- sumple atoms of different elements, one element only.
• Simplest organic compound that contains only carbon and hydrogen.

  Hydrocarbons
• Types of hydrocarbons:

  Alkane, Alkene, Alkynes
• Cyclic, planar compounds that resemble benzene. Other name of cyclic hydrocarbons is aromatic hydrocarbons.
• Alkanes- saturated hydrocrabons, single bond, plus 2.
• Alkenes- unsaturated hydrocarbons, double bond, as is.
• Alkynes- unsaturated hydrocarbons, triple bonds, minus 2.
• Hydrocarbons that don't have smell are called Arenes.
• Mass- the amount of matter in something. [Unit: kg]
• Weight- it is affected by the gravitational pull, the gravitational pull on mass. (Unit: N or newton)
• Avagadro's number: 6.02 × 10²³