Atoms Flashcards
Compounds
- Chemically bonded
- Cannot be separated
Mixture
- Physically mixed
- Can be separated
Element
- Only possesses one type of atom
Law of Conservation of Mass
Law of conservation of mass states that mass is neither created or destroyed
Law of Conservation of Energy
Energy cannot be created or destroyed, only converted
A+B = AB
A + B is reactants
AB is product
Period
- Row
- Number of electron shells (shells with electrons in them)
- 7 periods in total
Group
- Column
- Number of electrons they’ve got in the outer shell
- Outer shell = valence shell
- 18 groups in total
- 8 main groups
Charges
- If electrons are collected, a charge is given
- If there is a charge it is an ion
- If there is a positive charge it is a cation
- If there is a negative charge it is an anion
- If an electron is gained it has a - ion
- If an electron is lost it has a + ion
Metals
- Positive charge (cation)
- Loses electrons
Non-metals
- Negative charge (anion)
- Gains electrons
Ionic Bonding
- Positive and negative (metals and non-metals)
- Ionic bonds dissolve in water
- When ionic bonds dissolve in water, the water particles prevent the ions from sticking back together
The ions are then spread evenly throughout the water to create a solution - Electrons move to and from one another
- To balance electron numbers in outer shell
Balancing compounds
Li2O
Lithium = needs to lose 1 electron (non metal)
Oxygen = needs 2 electrons (metal)
Therefore, two lithium are needed to balance oxygen and lithium
Covalent bonding
- Negative and negative
- Only share electrons from outer shell
- When sharing, electrons move back and forth between elements
- Nonmetals and nonmetals join together
Covalent Bonding Example
E.g. H2O
- Hydrogen needs 1 electron (for a full outer shell) and
- Oxygen needs 2 electrons (for a full outer shell)
- H2O - there are 2 hydrogen atoms (1 more electron)
- The hydrogen atoms share their electrons to the oxygen atom to make a full outer shell (in the oxygen atom)
- The oxygen atom shares 2 of its electrons to the hydrogen atom to make a full outer shell (in the hydrogen atoms)