Counting atoms and elements Chemical Formulas Counting atoms and elements

First – some vocabulary Atom – the smallest particle of an element, that retains the chemical properties of that element Element – the smallest unit of matter that cannot be broken down by a chemical reaction Compound – a combination of two or more elements bonded together in some way

First – some vocabulary Ions – ions are electrically charged particle, formed when an atom gains or loses one or more electrons to form a stable outer shell Every time a chemical reaction happens, atoms gain, lose, or share electrons, causing atoms to become electrically charged

Charges on ions If a Sodium atom loses its valence electrons, what will the charge on the atom be? If a Calcium atom loses its valence electrons, what will the charge on the atom be? If a Chlorine atom gains electrons, what will the charge on the atom be?

Chemical formulas A chemical formula is a way to show the ratio of atoms in a compound Subscript – a small number, below the line of script, representing the number of atoms of that element

Objective: Determine the number of atoms of each element in chemical formulas containing subscripts

H2O Draw a t-chart Write the elements on the left Element symbols start with a capital letter Every capital letter is an element Write the subscripts on the right

Practice: SiCl4 H2SO4 Fe2O3 Na2CO3

If you have Parentheses: Fe(OH)3 Al(OH)3 Al2(SO4)3 OC(NH2)2