Chemistry Topic 1

Chemistry Topic 1

1. What atoms are and their structure

   • Atoms are the basic units of matter and the defining structure of elements. Atoms are made up of three particles: protons, neutrons and electrons. Protons and neutrons are heavier than electrons and reside in the center of the atom, which is called the nucleus
   • Atoms consist of electrons surrounding a nucleus that contains protons and neutrons. Neutrons are neutral, but protons and electrons are electrically charged. Protons have a relative charge of +1, while electrons have a relative charge of -1. The number of protons in an atom is called its atomic number.

2. Subatomic Particles

   • Mass number and atomic number The mass number of an atom is never smaller than the atomic number. It can be the same, but is usually bigger: The mass number of an atom is the total number of protons and neutrons it contains The atomic number of an atom is the number of protons it contains Notice that most of the mass of an atom is found in the nucleus.
   • Name of particle and Relative mass. Proton - 1, Neutron - 1, Electron - Very small (1/1836)

3. Chemical equations

   • Balanced symbol equations show what happens to the different atoms in reactions. For example, copper and oxygen react together to make copper oxide. Take a look at this word equation for the reaction: copper + oxygen → copper oxide Copper and oxygen are the reactants because they are on the left of the arrow. Copper oxide is the product because it is on the right of the arrow. If we just replace the words shown above by the correct chemical formulas, we will get an unbalanced equation, as shown here: Cu + O2 → CuO Notice that there are unequal numbers of each type of atom on the left-hand side compared with the right-hand side. To make things equal, you need to adjust the number of units of some of the substances until you get equal numbers of each type of atom on both sides. Here is the balanced symbol equation: 2Cu + O2 → 2CuO

4. Mixtures and how to separate them

   • Separating mixtures. The individual substances in a mixture can be separated using different methods, depending on the type of mixture. These methods include filtration, evaporation, distillation and chromatography.

5. Models of the Atom

   • Rutherford overturned Thomson's model in 1911 with his well-known gold foil experiment in which he demonstrated that the atom has a tiny, heavy nucleus. Rutherford designed an experiment to use the alpha particles emitted by a radioactive element as probes to the unseen world of atomic structure.
   • The Plum Pudding Model is a model of atomic structure proposed by J.J. Thomson in the late 19th century. Thomson had discovered that atoms are composite objects, made of pieces with positive and negative charge, and that the negatively charged electrons within the atom were very small compared to the entire atom.

6. Periodic Table and how it works

   • The common modern periodic table is organized by atomic number. From there we classify metals vs. non-metals (and metalloids) and group elements into Families like Alkali Metals, Halogens, and Noble Gases.

7. Group 1

   • The group 1 elements are found on the left hand side of the periodic table. They are called the alkali metals because they form alkaline compounds.

8. Group 7

   • The group 7 elements are also known as the halogens. They include fluorine, chlorine, bromine and iodine, which all have seven electrons in their outer shell.

9. Group 0

   • The group 0 elements are found on the right hand side of the periodic table. They are called the noble gases because they are very unreactive.