bonding, structure, and the properties of matter 🌺 Flashcards
1) what are ions?
2) how are they formed?
1) charged particles
2) when electrons are transferred (gained or lost) by a particle
how are ionic bonds formed?
describe the transfer of electrons and the charges of the ions formed.
> when a metal atom reacts with a non-metal atom,
electrons in the outer shell of the metal atom are transferred to the non-metal’s outer shell
> metal atoms lose electrons and become positively charged ions
non-metals gain electrons to become negatively charged ions
1) what charges do metals in group 1 and group 2 have?
2) what charges do non-metals in group 6 and group 7 have?
1)
group 1 has a charge of +
group 2 has a charge of 2+
2)
group 6 has a charge of 2-
group 7 has a charge of -
why do atoms transfer electrons?
to gain full outer shell (like noble gases) to gain a “stable electronic structure”
what is an ionic compound?
> a giant structure of ions
that are in a regular and repeating pattern called an ionic lattice
these ions are held together by strong electrostatic forces of attraction (ionic bonding)
between oppositely charged ions
these forces act in all directions in the lattice
what are the properties of ionic compounds?
> high melting and boiling points
since the strong electrostatic bonds between the ions require a lot of energy to be overcome
> when solid, ionic compounds can’t conduct electricity since the ions are held in place
if melted or aqueous, ions can move and therefore, conduct electricity
describe the limitations of these diagrams to represent compounds or molecules:
1) dot and cross
2) ball and stick
3) 2D model
4) 3D model
1) dot and cross diagrams fail to illustrate the 3D arrangements of the ions and they don’t indicate the relative sizes of the ions
2) the ball and stick model shows the arrangement of ions in a larger section ofa the crystal, but using sticks for bonds is misleading because the forces of attraction between ions actually act in all directions
3) the 2D model clearly shows the arrangement of ions in one layer, but it does not show how the next layer of ions is arranged
4) the 3D model only shows you the outer layer of ions
1) how are covalent bonds formed?
2) where do covalent bonds occur?
1) when non-metals share electrons and form a strong bond between them
2) in compounds of non-metals (h2O) and in non-metal elements (Cl2)
what are molecules?
2 or more atoms that are covalently bonded
what are the properties of substances that consist of small molecules?
> usually are gases or liquids
relatively low melting and boiling points
weak intermolecular forces
intermolecular forces are overcome, not the covalent bonds, when the substance melts or boils
intermolecular forces increase with the size of the molecules, so larger molecules have higher melting and boiling points
do not conduct electricity because the molecules do not have an overall electric charge
1) what is the chemical formula for ammonia?
2) and explain how it shares electrons.
1) NH3
2) a nitrogen atom has 5 electrons on its outer shell so it bonds with 3 hydrogen to gain a full shell
1) what is the chemical formula for hydrogenC?
2) and explain how it shares electrons.
1) H2
2) a hydrogen atom has 1 electron so they each share 1 electron to gain a full shell of 2 electrons
1) what is the chemical formula for chlorine?
2) and explain how it shares electrons.
1) Cl2
2) a chlorine atom has 7 electrons on it’s outer shell so each chorine atom shares 1 electron each to gain a full outer shell
1) what is the chemical formula for oxygen?
2) and explain how it shares electrons.
1) O2
2) an oxygen atom has 6 electrons on its outer shell so it shares 2 pairs of electrons to gain a full outer shell
1) what is the chemical formula for nitrogen?
2) and explain how it shares electrons.
1) N2
2) a nitrogen atom has 5 electrons on its outer shell so it shares 3 pairs of electrons to gain a full outer shell
1) what is the chemical formula for hydrogen chloride?
2) and explain how it shares electrons.
1) HCl
2) chlorine only needs 1 electron which hydrogen provides
1) what is the chemical formula for water?
2) and explain how it shares electrons.
1) H2O
2) 2 hydrogen atoms each share 1 electron from an oxygen atom
1) what is the chemical formula for methane?
2) and explain how it shares electrons.
1) CH4
2) carbon needs 4 electrons so 4 hydrogen atoms share 1 electron each
describe the atomical and electronic structure of metals.
> Metals consist of giant structures of atoms arranged in a regular pattern
> The electrons in the outer shell of metal atoms are delocalised and so are free to move through the whole structure
> The sharing of delocalised electrons gives rise to strong electrostatic attractions between the positive ions and negative electrons
> these attractions are known as metallic bonding and it’s very strong, meaning metals have a high melting and boiling point
1) why are metals good conductors?
2) why are metals malleable?
1) the delocalised electrons carry electric charge and thermal energy through the whole structure
2) metals are made up of layers of atoms that can easily slide over each other, meaning they’re easy to bend, hammer or roll
1) what are alloys?
2) what’s their purpose?
1) a mixture of metals
2) >pure metals are too soft for certain uses
>and so they’re mixed with different elements
>these different elements have different sized atoms which distorts the layers of the metal
>the distortion makes it harder for layers to slide over each other, meaning the alloy is overall harder
explain the properties of solids.
> strong forces of attraction between particles
particles are held together in a fixed position to form a very regular lattice arrangement
the particles don’t move, so solids keep a definite shape and volume
the particles vibrate about their position and they vibrate more when hotter, causing slight expansion
explain the properties of liquids.
> weak forces of attraction between particles
particles are randomly arranged and can freely move past each other but they tend to stick closely together
they have a definite volume but not shape and flow to fill the bottoms of containers
particles constantly move with random motion and move faster when hotter, causing slight expansion
explain the properties of gases.
> very weak forces of attraction between particles
particles move freely and far apart, travelling in straight lines
gases don’t keep a definite shape or volume and will always fill any container
the particles constantly move with random motion, moving faster when hotter causing expansion or increased pressure
