YR 9 CHEMISTRY

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What is ionic bonding

A chemical bond where two oppositely charged ions are electrostatically attracted to each other

What is electrostatic attraction

Attraction of cation to an anion

What is an ionic compound

When two or more ions become ionically bonded. Metal giving away electrons to a non-metal causing them to attract and bond

What happens when more and more ions bond

As more and more ions bond they form an ionic lattice

What is a lattice

Cations and anions side by side with no space in between held tightly due to electrostatic attraction on each cardinal plane.

How strong is an ionic bond

It’s extremely strong and you would need a large amount of energy and force to be able to break it.

Can you seperate an ionic bond

It is really easy to seperate an ionic bond making it brittle, blunt force causes a disruption and symmetry and causes ions to slide, this puts ions of the same charge next to each other causing them to seperate due to repulsion

What are the 3 rules for drawing a lattice

Show at least 3 layers and that it’s 3D, label the ions by their respective element (eg Na+ or Cl- )and leave no gaps and alternate between the charges.

How do u draw a electron transfer diagram

Draw electron shells of all M and NM that will be involved and put a plus between different elements, draw an arrow from each valence E in the M to the NM valence shell, draw an ⇨ to the result, draw new ions with new/complete shells, label everything and the results with + or -

What is the charge of an ionic compound

The charge is neutral

How many atoms does a polyatomic ion have

It has more than one atom eg OH-3, has oxygen and hydrogen, one compound gets one whole charge,

How do you name an ionic compound

Name the cation, + cation then drop it, than add suffix to anion and add anion but drop it.

eg. NaCl = sodium chloride

How do you name a transition metal in an ionic compound

Indicate the charge with roman number after the name (II) = anion = -2

iron(III)oxide = Fe+3O-2

What is a metallic bond

When a bond occurs between the same one type of cation. Electrostatic forces of attraction between the positively charged metal cations and negatively charged valence electrons occur in all directions, holding the lattice together.

Where does metallic bonding occur

It occurs in pure metals and metal alloys

Where does metallic bonding come from

It comes from metals shedding their valence electrons since they lose their outer shell easily, but since there is no anion the electrons just float around the cations.

eg. 3 sodium sheds 3 electrons

What is the delocalised sea of electrons

Many electrons that move around the bonded cations, they are mobile and randomly move around.

What does energy do to the electrons

Energy pushes electron in one singular same direction since they normally move randomly

How does metallic bonding become an crystal lattice

When electron shedded from the metals overlap each other to make a sea of electrons, causing the cation and electrons to be attracted. The attraction between cation and electrons everywhere that holds the bond together

What is a crystal lattice

Only made up of bonded cation that are close together and touch with a sea of electron all around

What is the best description for the sea of electrons

Random and mobile electrons that move all throughout the crystal lattice.

Are metallic bonds easy to seperate

They are hard to seperate but easy to move as they are malleable since the sea of electrons neutralises the repulsion of two cations next to each other so they can slide around without separating.

What are alloys

Alloys are a mixture of two or more elements where one element is a metal, combined via metallic bonding.

Why are alloys harder to break

Alloys are harder than pure metals since the cations are different sizes due to the atomic radius (distance from nucleus to valence electron)

What is an ion

A positively or negatively charged group or atoms or atoms, due to it dropping or gaining electrons changing it’s overall charge.

What are the two types of ions

Monatomic means it contains only one element that is charged, polyatomic means multiple elements that are charged

What happens when an atom loses or picks up an electron

When an atom picks up or loses an electron, it disrupts the balance between charges making the atom negative or positively charged, becoming an ion

How are ions formed

By the addition or removal of electrons from neutral atoms

Why do atoms become ions

They do this to try and achieve chemical stability, where they lose and gain atoms to have a full valence shell, satisfying duet or octet rule. It doesn’t matter how much a shell can hold as long as there is 8 in the valence, you can remove a shell

What is the duet and octet rule

Octet rule - atoms will drop and gain electrons to achieve 8 in its valence shell, excluding H and He with duet rule. Duet rule - atoms will drop and gain electrons to achieve 2 in its valence shell

What path do atoms take

Atoms will take the path of least resistance, if there 6 in valence then gain 2 not lose 6.

What is a cation

When an atom loses electrons and becomes a positively charged ion

What is an anion

When an atom gains electrons and becomes a negatively charged ion

Why do metals lose electrons

Group 1, 2, 3 are all cations, they have a loosely held valence so they can easily lose electrons. METALLOIDS ARE BOTH

Why do non-metals gain electrons

Group 15, 16, 17 are all anions, they are great attractors of electrons so they gain electrons easily. METALLOIDS ARE BOTH

What about group 4

In group 4 they don’t become cation or anions they prefer to share which is covalent bonding.

How do you name a cation

You just add cation to the elements name

How do you name an anion

You add ide as the suffix for its name and add anion after

What 3 subatomic particles make up an atom.

Protons, Neutrons and Electrons

What is the nucleus of the atom?

The nucleus is most of the atoms mass, it’s incredibly dense and made from protons and neutrons and held by nuclear force.

What are the charges of the subatomic particles?

Proton - positive(+1)

Neutron - neutral(0)

Electron - negative(-1)

What are the sizes of the subatomic particles relative to a proton

Proton - 1

Neutron - 1

Electron -1/1800

Why is the nucleus dense

Protons and neutron are relatively equal mass and are huge in comparison to electrons.
This is why the nucleus is dense.

What makes up the mass of the atom

Proton and neutrons

What is an electron orbit (Bohr model)

Electrons revolve around the nucleus in fixed, circular orbits,

How does energy correlate to electron orbit

The electrons’ orbits correspond to specific energy levels in the atom.can only occupy fixed energy levels and cannot exist between two energy levels

The Bohr model suggests that electrons were grouped in

different energy levels, called electron shells. From n1 - n7, with 1 being the lowest and 7 being the discovered highest, meaning electrons have more energy. All electrons in the same shell have the same energy and therefore same spin.

Why do electrons in n1 have less energy(speed)

Because of the electrostatic attraction that is more powerful since the electrons are closer, so it takes more energy and is harder for them to move(spin) since they are bound.

How is the atom that makes up the element determined

The type of atom that makes up each element is determined by the number of protons (atomic number) in the nucleus. 

What determines the atomic number

The number of protons in the nucleus of the atom, same amount of proton = same element

What determines the mass number (weight of atom/nucleus)

The total number of protons + neutrons in the nucleus, (electrons weight is so small they don’t contribute)

What does it mean if an atom is electrically neutral

Therefore number of electrons = number of protons 

What is the equation to find the number of neutrons

Atomic mass - atomic number

All atoms that belong to the same element have the same number

of protons in the nucleus and therefore the same atomic number, Z. 

What are isotopes

Atoms that have the same number of protons (atomic number) but different numbers of neutrons (and therefore different mass numbers)

Do all elements have isotopes

All elements have isotopes even hydrogen has 3

Which isotope appears on the periodic table determining the atomic weight?

It is determined by the most abundant type of isotope in the element found in nature

What do isotopes have

identical chemical properties but different physical properties such as mass and density. In particular, some isotopes are radioactive

What does the proton determine

An atoms elemental identity, as well as the number of electrons and the atomic number

What does the electron determine

Chemical reactivity (more change = reactivity) and properties, an atoms participation in chemical reactions and change.

What does the neutron determine

The physical properties of an atom like its mass and density

What if an isotope is too big and heavy

The heaviest isotope (mass) is the most radioactive. If the nucleus gets too big, the atom can’t sustain itself this is nuclear decay, to stop the decay it’ll eject neutrons from the nucleus to be lighter changing isotopes.

What is transmutation

When subatomic particles change to avoid being ejected, a neutron will become a proton to not be ejected. This changes elemental identity such as gold = mercury.

What is electron configuration

How electrons are configured around an atom

What are the two rules for electron configuration

Rule 1. Each shell can only contain a maximum number of electrons.

Rule 2. Lower energy shells fill before higher energy shells.

What is the formula for how many electrons a shell can hold

n-2n², n1 - 2, n2 - 8, n3 - 18, n4 - 32

How does electron configuration work for the first 20 elements

If its the 19 or 20 element, n3 only goes up to 8 and then you start on the fourth shell. From n4 upwards for the first 20 elements N2, 3 and 4 all hold 8 except for n1.

What is valence

The outermost electrons and shell

What are the patterns in electronic configuration

Same group have the same amount of valence electrons in valence shell this matches the group number. Same periods have the same number of shells.

What is matter

Matter is any substance that has a volume (takes up space) and has a mass (g, kg)

What is matter made of?

All matter is made of atoms which can bond together to produce different substances

Everything is either a:

Matter or energy

The relationship between matter and energy can be described as?

Energy changes matter and matter changes energy

What is an atom?

Is the building block of matter made of subatomic particles such as protons, neutrons, and electrons. It is the smallest particle of an element

What was the first atomic theory?

In 1802, John Dalton presented the first theory that all matter is made tiny round particles which are indivisible and indestructible.

Why was John Dalton’s theory wrong?

John Dalton was wrong because atoms are in fact made of smaller subatomic particles, protons, neutrons and electrons.

What are the two groups matter can be spilt into?

Pure substance and Mixture

What is a mixture

Consists of two or more different types particles (eg. elements, compounds) that are not chemically bonded together, and are just floating around not bonded to each other.

What are the two types of mixtures

Homogeneous and heterogeneous

What is a homogenous mixture

Is a type of mixture where the components are evenly distributed and appear uniform (look the same) throughout, the components remain the same wherever you check.

eg, air, salt water

What is the composition of something?

The composition is how something is made up, like the kinds of atoms and molecules in the substance.

What is a heterogeneous mixture?

Is a type of mixture where the components are not evenly distributed and aren’t uniform (don’t look the same), you can see the different parts. The composition changes based off of where you check.

eg. oil and water, sand and gravel.

In what ways can a mixture be seperated?

A mixture can be separated by chemical and physical means. eg. filtration

What is a pure substance?

It’s made up of only one type of particle (element or compound), it has a fixed composition and consistent properties wherever you check. The particles can be made the same or different elements, but it must consist of the same particle.

What are the two types of pure substances?

Elements and compounds.

What is an element?

Types of atoms that share the same amount of protons. In substances this means that they are made up of one or more of the same type of atom.

What can elements exist as?

Elements can be monatomic (just existing as a singular atom, only elements can be monatomic) or polyatomic (existing as two or more of the same atoms chemically (covalently) bonded together). Regardless of its form an element can only be made up of one type of atom. eg. O2, Ne, O3

How can a element be separated?

Elements cannot be separated into simpler substances (only one type of individual atom) by chemical or physical means, as they consist of only one type of atom and are the simpler substance.

What is a simpler substance

A substance that cannot be broken down into simpler components by chemical means. And is often composed of a single type of atom, such as elements.

What is a compound

A compound is a substance made up two or more different elements chemically bonded together to make a new substance. eg H2O, NaCl

How can a compound be seperated?

A compound can only be separated by chemical mean and not physical ones.

How can pure substances be seperated?

Elements cannot be separated, while compounds can be broken down into simpler substances. Compounds can only be separated through chemical means not physical.

How to identify if substances is pure substance or mixture?

If it can be separated by a physical process i.e filtration, it’s a mixture, if not it’s a pure substance.

How to identify if mixture is homogenous or heterogenous?

If it is totally uniform (looks the same) then it’s homogenous, if not it’s heterogenous.

How to identify if pure substances is an element or compound?

If it can be broken down by a chemical process it’s a compound. If not it’s an element.