Science

Running head : SCIENCE

Science

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Science

Chemical change is the change in substances that produces other substance of different chemical and physical properties . It is characterized by the process of chemical reaction . An example of chemical change is the burning of sugar or paper . In this process , the color and chemical composition of the material changed . Moreover , the process cannot be reversed . A burned paper cannot be made back to its original state , so as the sugar . For some materials , the only way of

br reversing the change , if possible , is by chemical means only

The bond between atoms is called chemical bond (Capri , 2003 . In general , there are two types of chemical bonds namely the ionic and the covalent . In ionic bond , the some electrons of an atom are transferred to the atoms it will bond . However , for covalent bonds , the atoms share some of the electrons . The electrons that interact in the bonding are the valence electrons . These are the electrons on the outermost shell of the atom . A way to determine the number of valence electron of an atom is by writing its electron configuration . The electron configuration of H is 1s . This means that its valence electron is 1 . For O , the electron configuration is 1s2 2s2 2p6 . The valence electrons for this configuration lie on the 2s and 2p subshells , which have 8 electrons in total . However , for some atoms or elements that have d subshells , the valence electrons can also include the...