IONS AND BONDINGYou will notice that not all the atoms have fully filled outer valence shell from the belowdiagram which only shows the number of electrons in the valence shell.Is there a pattern you see here?Also notice that the last column (He and Ne) are known as unreactive noble gases, why doyou think that is so?For the pattern,_________________________________________________________________________For the last column, noble gases have ____________________________, therefore they donot need to react with other atoms to be stableHelium does not have 8 electrons in its outer shell, it only has 2 so for helium we say it has_____________ electronic configurationWhereas all the other noble gases have 8 electrons in their valence shells and hence, can bedescribed has having ____________________________.All atoms like to have octet valence shells, this is very important.Notice that group 1-3 fall under metalsWhile group 4 to 8 fall under non-metals
Because metals have fewer valence electrons, they prefer to_____________________________ and enjoy the stability provided by an octet electronicconfiguration.What happens when an atom gives away electrons?Notice that a sodium atom has 11 protons and that number of protons will never change. Butyet if it has given 1 electron away, how many electrons does it have left? _____What happens is sodium has 1 more proton than electron, and we know that protons have apositive charge of +1 And that atom changes from being neutral to being an______ that has a charge of ______ As the diagram shows, a +1 ion produces an__________________ that can attract or repel other charged particles! Solidify your understanding! 1) what is the ion formed by atoms ofmagnesium, boron, and lithium when they lose their electrons?_________________________For non-metals, they can get aoctet valence shell through 2 ways.
The first way is to gain electrons.Nitrogen needs to gain ____ more electrons to reach octet configuration.Oxygen needs to gain ____ more electrons to reach octet configuration.Similar to the example on sodium above, when a non-metal atom such as fluorine atom gainsan electron, suddenly it has 10 electrons and only 9 protons and it has become an ______ witha charge of -1Solidify your understanding!1) what is the ion formed by atoms of chlorine and sulphur when they gain some electrons?____________________Draw out the ions formed below.2) what is the electronic configuration of sulphide (S2-) and oxygen ion?____________________________________________But in order to gain electrons, non-metal atoms need to come into contact with ___________atoms.The transfer of electrons from metal to non-metal atoms results in ions of____________________ being formed. Unlike charges cause them to be attracted____________ to each other.Obtaining the formula for ionic compounds
An ionic compound is always made up of _______ positively charged ions and_________________ negatively charged ions.The ________________ of the ions always equal to ______, because the number of electronsgiven to form the positive ions is equal to the number of electrons gained to form the negativeions3 simple steps to follow to get the formula of an ionic compound1. Determine the charge of the metal positive ion using the periodic table2. Determine the charge of the non-metal negative ion using the periodic table3. Find the LCM of both charges to get the numbers of each ion in the compoundTry to find out the formula of 1) Magnesium Chloride and 2) Lithium Oxide_______________________________________________________Harder example: try to find the formula of Aluminium Oxide______________________________________________________There are also some ions which are not found in the periodic table such as _______________ion which is NH4+, and ____________ ion which is SO42-, as well as ___________ NO3- and____________ CO32-.Find out the chemical formula of ammonium sulphate ___________________Take note that in your formula, the metal ion should always be first (such as NaCl) and bigions like sulphate or nitrate should be in brackets like in Mg(NO3)2.COVALENT BONDINGA covalent bond is defined as the _______________________________ between_________________. And take note that covalent bonds only apply to non-metal atoms.Below are a few examples
Now you can try to form dot-and-cross diagrams of the following molecules, do not forget toinclude a legend, which is worth marks in exams!1. Br2 2. F2Some of the harder ones involve many atoms so you need to know which atoms are in thecentre of the molecule. The more number of covalent bonds an atom need to get octetconfiguration, the more likely it is to be in the centre bonding to many other atoms.1. N2 2. NH3 3. CH4ELEMENTS AND ATOMS CHECKLISTAn atom with more electrons than protons is known as a1) neutral charged neutron2) positively charged ion3) positively charged atom4) negatively charged ionWhich of the following statement is true?1) a proton is as heavy as an electron but lighter than an neutron2) a proton is as heavy as a neutron but lighter than an electron3) a proton is as heavy as a neutron but heavier than an electron4) a proton is as heavy as an electron but heavier than a neutronAtoms are arranged in the periodic table by1) number of protons and in groups2) atomic number and in terms of total number of electrons3) number of groups and protons4) alphabetical orderWhat is the maximum number of electrons in the second shell of an atom?1) 1
2) 23) 34) 8What is the difference between a molecule of an element (like H2 gas) and a molecule of acompound (like H2O)?____________________________________________________________________________________________________________________________________________________What is the formula of Magnesium Oxide?_________________Draw the electronic configuration of HeliumDraw a diagram of Sodium Chloride showing the ions of Sodium and Chlorine.Draw the dot and cross diagram of H2O, together with a legend.Good job! ^_^
Solidify your understanding!1) what chargeLet me introduce a very important organic molecule called glucose.It has a chemical composition, meaning it is made up of how many atoms and of whichelement, of6 carbon atoms, 12 hydrogen atoms and 6 oxygen atoms