Science 9 - Chapter 3 Test Flashcards
difference between elements and compounds
elements are pure substances that cannot be broken down into simpler substances whereas compounds are pure substances composed of two or more elements.
why do some elements form compounds while others do not?
elements bond to form compounds because they want to fill their outer shell. when the valence shell is full, the atom does not need to gain or lose and electrons and is unreactive.
difference between ionic compounds and covalent compounds
covalent compounds = transferred electrons
ionic compounds = shared electrons
describe ionic bond
Atoms take or receive electrons from other atoms, once the transfer is complete they magnetize together and form what is called an ionic bond.
what information is given by a chemical formula
The chemical formula of an ionic compound contains symbols to identify each ions and shows relative numbers of ions in the compound
difference between atom and ion structure
number of electrons in outer shell altered by exchange of electrons. atoms have no charge, ions have charges
covalent compound
- both parts have negative ion charge
- mono, di, tri naming
- covalent bond (shared electron)
- bohr diagram electrons shared
ionic compound
- first part has positive ion charge last part has negative ion charge
- “normal” naming
- ionic bond (ions - one gained electron(s), the other lost electron(s)
- bohr diagram elecrons not shared
why is the periodic table called the periodic table?
periodic means to recur regularly. in the periodic table there are certain characteristics that are periodic that is, regularly recurring
bohr diagrams
electrons exist outside the nucleus, but they have certain levels that they occupy. we call these levels bohr electron shells, and they are part of a theory called the bohr atom.
