P1 - Bonding, Structure and Properties Flashcards
What are ions ?
Charged particles, formed when atoms gain/lose electrons to form a full outer shell which is very stable. Metal atoms form positive ions where non-metals form negative ions.
What is an ionic bond ?
Where oppositely charged ions are strongly attracted to one another by electrostatic forces.
What groups’ elements most readily form ions ?
Groups 1, 2 and 6, 7.
What does an elements group number affect ?
The number of electrons in its outer shell, all elements in a group have the same number of electrons in their outer shell.
What does an elements period number affect ?
The number of electron shells an atom has.
What is a dot and cross diagram ?
Show how ionic bonds are formed, show the arrangement of electrons in an atom/ion.
What is bad about dot and cross diagrams ?
They don’t show the structure of the compound, the size of the ions or how they’re arranged.
How are ionic compounds arranged ?
In a structure called a giant ionic lattice, where ions form a closely packed regular lattice arrangement. Very strong electrostatic forces of attraction between opposite ions in all directions in the lattice.
What are the properties of ionic compounds ?
High melting and boiling points due to many strong bonds between ions taking a lot of energy to overcome, when solid can’t carry current as no moving charged particles, when molten ions can move and carry a current, some can be in solution - ions separate and can carry a current.
What is an empirical formula ?
A formula giving the proportions of elements present in a compound, not actual numbers or arrangements of atoms.
How can you find the empirical formula of an ionic compound ?
In a dot and cross count up how many atoms there are of each element, if it’s a 3D diagram use it to work out the ions in the compound, and then balance the charges of the ions to give a net charge of zero.
What type of atoms does covalent bonding happen between ?
Non-metals.
How are atoms bonded in covalent compounds ?
They share electrons, the positively charged nuclei are attracted to the shared pair of electrons by electrostatic forces making covalent bonds strong. Each atom makes enough covalent bonds to fill its outer shell.
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