Why do atoms form compounds?
To become more stable, which is when their outer electron level is full (containing 8 electrons).
To achieve this, atoms will combine when the compound formed is more stable than it's separate atoms.
Atoms gain or lose electrons to become stable. They now have a different number of electrons compared to protons.
A positively charged ion
A negatively charged ion
An atom that has gained or lost an electron
the force of attraction between the oppositely charged ions in an ionic compound and it occurs between metals & nonmetals
Formed when atoms are held together by ionic bonding. Their solution conduct electricity.
The attraction forces between atoms when they share electrons. Forms between nonmetals.
the neutral particle formed as a result of covalent bonding where outermost energy levels overlap and electrons are shared. Most are liquids or gases at room temperature.
Types of Covalent Bonds
- single bonds (made up of 2 shared electrons)
- double bonds (2 pairs)
- triple bonds (3 pairs)
A group of covalently bonded atoms that act as one ion. Formed by both ionic & covalent.
One that has a slightly positive end and a slightly negative end although overall the molecule is still neutral
Two atoms that are exactly alike in sharing their electrons equally
- name of elements in compound
- number of atoms of each element
one composed of two elements
Positive or negative number assigned to an element to show its combining ability in a compound
1+ 2+ 3+ 4± 3- 2- 1- 0
Writing Formulas for Binary Compounds
1. Write the symbol of the element with the positive oxidation number
2. Write the symbol for the element with the negative oxidation number next
3. Look up the oxidation numbers for each element and write it above the symbols
4. Crisscross the numbers only - not the signs - and write the oxidation number of one element as the subscript for the other. Do not write the number 1 as a subscript.
Check - sum of oxidation # 's must be zero.
Writing Formulas for Compounds with Polyatomic Ions
1. Write the symbol of the element or ion with the positive oxidation number.
2. Write the symbol for the element (or polyatomic ion) with the negative oxidation number.
3. Look up the oxidation numbers for each element or ion and write it above the symbols.
4. Crisscross the oxidation numbers to become the subscripts and reduce the subscripts to te smallest whole numbers. If more than one polyatomic Ion is used, write parentheses around the polyatomic ion before adding the subscript.
5. Check that the sum of oxidations numbers is zero.
Difference with Transition Metals
1. Write the name of the element which is the positive ion.
2. If the ion has only one possible oxidation number, proceed
If the element is a transition metal, check your oxidation # chart to see if it has a variable oxidation number.
If it does, determine the oxidation number of the ion from the formula of the compound. Non metals never have more than one oxidation number!
Remember, the overall charge must be 0.
Write the charge of the positive ion using roman numerals in parentheses after the ion's name.
3. They end in -ide.
Writing Names for Binary Covalent Compounds
Use the prefixes to indicate how many atoms of each elements are in the binary covalent compound.
mono, di, tri, tetra, penta, hexa, hepta, octa