bonding, structure, and the properties of matter 🌺

Question 1

1) what are ions?

2) how are they formed?

Answer 1

1) charged particles

2) when electrons are transferred (gained or lost) by a particle

Question 2

how are ionic bonds formed?
describe the transfer of electrons and the charges of the ions formed.

Answer 2

> 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

Question 3

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?

Answer 3

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 -

Question 4

why do atoms transfer electrons?

Answer 4

to gain full outer shell (like noble gases) to gain a “stable electronic structure”

Question 5

what is an ionic compound?

Answer 5

> 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

Question 6

what are the properties of ionic compounds?

Answer 6

> 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

Question 7

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

Answer 7

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

Question 8

1) how are covalent bonds formed?

2) where do covalent bonds occur?

Answer 8

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)

Question 9

what are molecules?

Answer 9

2 or more atoms that are covalently bonded

Question 10

what are the properties of substances that consist of small molecules?

Answer 10

> 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

Question 11

1) what is the chemical formula for ammonia?

2) and explain how it shares electrons.

Answer 11

1) NH3

2) a nitrogen atom has 5 electrons on its outer shell so it bonds with 3 hydrogen to gain a full shell

Question 12

1) what is the chemical formula for hydrogenC?

2) and explain how it shares electrons.

Answer 12

1) H2

2) a hydrogen atom has 1 electron so they each share 1 electron to gain a full shell of 2 electrons

Question 13

1) what is the chemical formula for chlorine?

2) and explain how it shares electrons.

Answer 13

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

Question 14

1) what is the chemical formula for oxygen?

2) and explain how it shares electrons.

Answer 14

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

Question 15

1) what is the chemical formula for nitrogen?

2) and explain how it shares electrons.

Answer 15

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

Question 16

1) what is the chemical formula for hydrogen chloride?

2) and explain how it shares electrons.

Answer 16

1) HCl

2) chlorine only needs 1 electron which hydrogen provides

Question 17

1) what is the chemical formula for water?

2) and explain how it shares electrons.

Answer 17

1) H2O

2) 2 hydrogen atoms each share 1 electron from an oxygen atom

Question 18

1) what is the chemical formula for methane?

2) and explain how it shares electrons.

Answer 18

1) CH4

2) carbon needs 4 electrons so 4 hydrogen atoms share 1 electron each

Question 19

describe the atomical and electronic structure of metals.

Answer 19

> 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

Question 20

1) why are metals good conductors?

2) why are metals malleable?

Answer 20

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

Question 21

1) what are alloys?

2) what’s their purpose?

Answer 21

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

Question 22

explain the properties of solids.

Answer 22

> 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

Question 23

explain the properties of liquids.

Answer 23

> 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

Question 24

explain the properties of gases.

Answer 24

> 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

Question 25

what are the limitations of the particle theory diagram to represent the different states of matter?

Answer 25

> in the model there are no forces

> all particles are represented as spheres whereas that’s not the case in particles

> the spheres are solid which particles are not

Question 26

describe the structure and properties of polymers

Answer 26

> made up of atoms that are linked together by strong covalent bonds

> strong intermolecular forces so they’re solid at room temperature

> weaker intermolecular forces than ionic bonding, so they have low melting and boiling points

Question 27

describe the structure and properties of giant covalent structures

Answer 27

> all of the atoms in these structures are linked to other atoms by strong covalent bonds
these bonds are hard to overcome so they have high melting and boiling points

Question 28

give examples of giant covalent structures

Answer 28

> diamond
carbon
silicon dioxide (silica)

Question 29

describe the properties of diamond in terms of structure and bonding

Answer 29

> made up of carbon atoms that form covalent bonds with 4 other atoms
very high melting ad boiling point due to strong bonds
no free electrons or ions so no conduction of electricity

Question 30

describe the properties of graphite in terms of structure and bonding

Answer 30

> each carbon atom forms 3 bonds, creating sheets of carbon that are arranged in hexagons
no covalent bond between layers they’re held together weakly so they can freely move over each other
graphite is very soft and slippery, ideal for lubricating material (˵ ͡° ͜ʖ ͡°˵)
due to the strong covalent bonds IN the layers, the melting points are high
as only 3 of the 4 electrons in the outer shell of carbon are used in bonds, each atom has 1 delocalised electron which means graphite can conduct electricity and thermal energy

Question 31

what is graphene and its uses/potential?

Answer 31

> graphene is a single layer of graphite, making it a 2D substance
the covalent bonds make it very strong but its also very light
they can be added to composite materials to add strength but not much weight
delocalised electrons makes it able to conduct electricity, giving it potential in electronics

Question 32

what are fullerenes and their uses?

Answer 32

> fullerenes are molecules of carbon atoms with hollow shapes (tubes or balls)
they’re made up of hexagonal rings of carbon atoms but they can contain rings with 5 or 7 carbon atoms
the first fullerene to be discovered was Buckminsterfullerene (C60) which has a spherical shape
they can ‘cage’ other molecules, making them useful for delivering drugs
they have a huge surface area which catalysts can be attached to, they also make great lubricants

Question 33

what are carbon nanotubes and their properties and uses?

Answer 33

> cylindrical fullerenes with very high length to diameter ratios
they can conduct electricity and thermal heat
they have high tensile strength (they don’t break easily when stretched)
nanotubes are part of the study of nanotechnology
they can be used in electronics or to strengthen materials without adding much weight

Question 34

what is nanoscience?
give the sizes of nanoparticles and other small particles.

Answer 34

> the study of structures that are 1–100 nm in size (1 x 10-9 to -7)

> fine particles have diameters between 100 and 2500 nm (1 x 10-7 m and 2.5 x 10-6 m)

> Coarse particles have diameters between 1 x 10-5 m and 2.5 x 10-6 m and are referred to as dust

Question 35

how does the size of a particle affect it’s surface area?

Answer 35

as the size of a particle decreases, the surface area increases

as the size of the particle decreases by a factor of 10 the surface area to volume ratio increases by a factor cubes of 10

Question 36

what can nanoparticles be used for?

Answer 36

> nanoparticles have a huge surface area to volume ratio which can be used to help make new catalysts

> nanomedicine is also a possibility because the tiny particles are more easily absorbed by the body than most particles

> some nanoparticles conduct electricity which can be used in tiny electric circuits for computer chips

> silver nanoparticles have antibacterial properties which can be added to polymer fibres that can then be used time surgical masks, wound dressings, and deodorants

> nanoparticles are also used in cosmetics to improve moisture without being oily

> Nanoparticles are also common in sunscreens, they provide better skin coverage and more effective protection from the sun’s ultraviolet rays

Question 37

why are nanoparticles also seen as risky and how can this be overcome?

Answer 37

> the effect of nanoparticles on the body isn’t fully understood
so it’s important that any new products are thoroughly tested to minimise the risks
since it’s not clear whether or not the particles can get in your body ad damage cells or if they damage the environment when they’re washed away
people are worried that nanoparticles have been made available before the effects on human health have been investigated properly
so they believe that products containing nanoparticles should be clearly labelled to give customers a choice