Found in the top left hand corner of each element box in the periodic table it tells youthe number of protons in each atom of an element. It will also tell you the number ofelectrons as this is equal to the number of protons. Example: Atomic number for Carbonis 6c)Atomic weightAverage weight of one atom of an element it is measured in atomic mass units which areequal to one twelfth the weight of a carbon atom. Example atomic weight of carbon is12.0107 units12Complete the following tableGroupNumber of electrons in outer shell (Valence electrons)Alkali metals1Alkali Earth metals2Noble gases8Halogens713What is a period?It is a row in the periodic table whereas a group is a column- 14 -© Video Education Australasia Pty Ltd 2009Reproducing these teacher notesYou may download and print one copy of these teacher notes from our website for your reference. Further copying or printing must bereported to CAL as per the Copyright Act 1968.
What Are Atoms Made of?14Complete the following table.Shell numberNumber of electrons in shell1228318432550a)Explain how you find the answer.The number of electrons in a shell is twice the square of the shell number.15Why is an element with only one electron in its outer shell very reactive?It is very easy to lose the electron to other atoms. a)What about an element that only needs one more electron to fill its outer shell? This loss of an electron is chemical reactivity, similarly, gaining an electron to fill a shellthat only needs one more is also reactivity.b)Give an example for each of the above.Sodium only needs to loose one electron to have a full outer shell and chlorine only needsto gain an electron for its outer shell tobe full.16What happens when Sodium and Chlorine react?They form a totally new substance with very different appearance and properties but with theatoms in a ratio of one to one.a)How is this different from a mixture?A mixture has similar properties to its ingredients and it is possible to separate them 17What is the difference between ionic bonding and covalent bonding?Ionic bonding occurs when atoms gain or loose electrons to form negative and positive ions.These oppositely charged ions are attracted to each other and the bond between them iscalled an ionic bond. Covalent bonds are formed when atoms have a full outer shell ofelectrons by sharing electrons18What is a cation? A cation has lost at least one electron and has a positive charge.19An anion?An anion has gained at least one electron and has a negative charge20Write a chemical equation for what happens when: Potassium combines with chlorine to produce Potassium ChloridePotassium + ChlorinePotassium ChlorideK+ClKClThe combination of Carbon with oxygen to produce Carbon dioxide. Carbon + OxygenCarbon dioxideC+O2CO221What do you think the di in dioxide stands for?Di means 2. There are 2 Oxygen atoms to each Carbon- 15 -© Video Education Australasia Pty Ltd 2009Reproducing these teacher notesYou may download and print one copy of these teacher notes from our website for your reference. Further copying or printing must bereported to CAL as per the Copyright Act 1968.
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