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The topic that fascinated me the most in my Science lessons this year is the Periodic Table and its power of predicting the existence and properties of elements yet to be discovered. Dimitri Mendeleev placed the 65 known elements of his time into a grid table and observed gaps in the table. Based on the position of gaps in the table, he predicted the existence of undiscovered elements and their properties even before they were found. Subsequently, these elements such as germanium, gallium and scandium were found and their physical and chemical ‘behaviour’ were just as Mendeleev predicted! Hence, even though Mendeleev did not physically stumble upon these elements, he could be said to have discovered them. Why is Mendeleev able to predict the properties of undiscovered elements just by looking at the Periodic Table? I learnt that this is because the Periodic Table is designed to classify elements based on their observed chemical properties and their atomic number (number of protons). Hence, the Periodic Table shows trends and patterns as we move horizontally across a Period and vertically across a Group. The trends and patterns are captured in this version of the Periodic Table obtained from the Internet: Moving across the period, I noticed that each atom of the element has one more electron. These electrons are arranged in a certain configuration consisting of layers called shells. The shell closest to the nucleus contains only two electrons and the subsequent shells contain a maximum of 8 electrons. The electrons in the outermost shell (also known as the valence shell) participated in chemical reactions. Therefore, for a metal, how readily a metal atom surrenders its electrons depends on how far away the negatively charged nucleus and how many valence electrons are there. The nucleus of a bigger metal (e.g. magnesium) exerts a smaller pull on its valence electron because the valence electron is further away. It therefore loses its electron readily to a halogen atom (e.g. chlorine). Beryllium, a much smaller metal atom, can hold on to its valence electron when partnering a chlorine atom because its valence electron is nearer to the positively charged nucleus. Therefore, Beryllium forms covalent bonds where it shares the electron with chlorine. An atom is happiest when its shell is fully filled and these atoms form the noble gases group. Every atom aspires to become its closest noble gas, with the outermost shell fully filled with 8 electrons. Hence, sodium, which has only one electron in its valence shell, is happy to give up its atom to become similar to Neon. However, unlike Neon which is neutral, Sodium attains the electronic configuration of Neon but is positively charged. Calcium is also quite happy to give up two electrons to attain the electronic configuration of Argon. However, when the atom has 3 or 4 electrons, it is more unwilling to give them up to a partner as that seems too much to lose for a partnership. So, they prefer to share the electrons in a more equal, covalent-style relationship. Atoms are like human beings, some more generous and some more selfish. I found this sweet little poem portraying ions as lovers: I am attracted to you Like an electron to a proton Together we form an ionic bond Though we are opposite charged ions I am drawn towards you Our love is unique as an orbital For only two electrons can fill this space As my love for you increases My energy level rises I am in this excited state Increasing the tendency to form a chemical bond I was an element It took you to make me a compound substance Falling in love with you is a chemical reaction Which cause my love for you to grow Ours is an exothermic love Each giving of love not just absorbing it Sometimes you do something especially nice Which speeds up the chemical process Like a catalyst in my increasing love for you I realise we have our inhibition periods And sometimes I am selfish enough To be an endothermic reaction Only absorbing your love The feeling i have for you is so intense It cannot be measured in kilojoules Often I have to make a qualitative elementary analysis To understand and love you more But i don't expect to know your empirical formula You are too complex a person for that WHEN YOU ARE GONE I AM A NOBLE GAS AN INERT SUBSTANCE WHEN I AM WITHOUT YOU THE WORLD SEEMS STILL AND I AM AT EQUILIBRIUM... Chemistry is so much fun!