Y10 Chemistry AI

What are the three subatomic particles in an atom?

Protons, neutrons and electrons.

What is the charge of a proton?

+1 (positive).

What is the charge of a neutron?

0 (neutral).

What is the charge of an electron?

−1 (negative).

Where are protons found?

In the nucleus of the atom.

Where are neutrons found?

In the nucleus of the atom.

Where are electrons found?

In electron shells (energy levels) around the nucleus.

What is the relative mass of a proton?

1.

What is the relative mass of a neutron?

1.

What is the relative mass of an electron?

Approximately 0.0005.

Which part of an atom contains almost all its mass?

The nucleus, which contains the protons and neutrons.

What is an element?

A substance made of atoms with the same number of protons.

What determines which element an atom is?

Its number of protons.

What is the atomic number?

The number of protons in the nucleus of an atom.

What is the symbol convention for chemical elements?

A one- or two-letter symbol; the first letter is capitalised.

Give an example of an element symbol that comes from an older name.

Gold is Au.

What is an isotope?

Atoms of the same element with the same number of protons but different numbers of neutrons.

Why are isotopes atoms of the same element?

They have the same number of protons.

What differs between isotopes of the same element?

Their numbers of neutrons, and therefore their mass numbers.

What is the mass number?

The total number of protons and neutrons in an atom's nucleus.

How do you calculate the mass number?

Mass number = number of protons + number of neutrons.

How do you calculate the number of neutrons?

Neutrons = mass number − atomic number.

In isotope notation, what does the larger upper number represent?

The mass number (protons + neutrons).

In isotope notation, what does the smaller lower number represent?

The atomic number (number of protons).

What does the notation C-12 tell you?

A carbon isotope with mass number 12.

How many protons and neutrons are in C-12?

6 protons and 6 neutrons.

How many protons and neutrons are in C-13?

6 protons and 7 neutrons.

How many protons and neutrons are in C-14?

6 protons and 8 neutrons.

How many protons and neutrons are in H-1?

1 proton and 0 neutrons.

How many protons and neutrons are in H-2?

1 proton and 1 neutron.

How many protons and neutrons are in H-3?

1 proton and 2 neutrons.

How many protons and neutrons are in Cu-65?

29 protons and 36 neutrons.

How many electrons does a neutral atom have?

The same number of electrons as protons.

What are electron shells?

Layers or energy levels around the nucleus in which electrons are arranged.

In what order do electron shells fill?

From the innermost shell outwards.

Can an outer shell begin filling before the inner shell is full?

No. Inner shells fill before electrons are added to shells further out.

How many electrons can the first shell hold?

2 electrons.

How many electrons can the second shell hold (for the first 20 elements)?

8 electrons.

How many electrons can the third shell hold (for the first 20 elements)?

8 electrons.

How many electrons can the fourth shell hold (for the first 20 elements)?

2 electrons.

What is an electron shell diagram?

A diagram showing electrons as dots or crosses on concentric shells around a nucleus.

What are valence electrons?

The electrons in an atom's outermost electron shell.

What is the valence shell?

The outermost electron shell of an atom.

What is a Lewis (electron dot) diagram used to show?

The valence electrons of an atom or ion around its chemical symbol.

How are valence electrons represented in a Lewis dot diagram?

As dots or crosses around the element symbol, without drawing shells.

How are positive ions shown in Lewis dot diagrams?

In square brackets with the charge outside; the diagram shows no valence dots after the atom loses them.

How are negative ions shown in Lewis dot diagrams?

In square brackets with the charge outside; the outer shell is shown filled (usually 8 dots).

How are ions arranged in an ionic-compound Lewis diagram?

Positive ion first, followed by negative ion; use a number in front if multiple ions are needed.

How are electrons represented in a Lewis diagram of a covalent molecule?

As shared pairs between atoms; shared electrons count towards the outer shells of both atoms.

What is an electron configuration?

A way of writing the number of electrons in each shell, in order, separated by commas inside brackets.

What is the electron configuration of carbon?

(2,4).

What is the electron configuration of calcium?

(2,8,8,2).

What is the electron configuration of oxygen?

(2,6).

What is the electron configuration of phosphorus?

(2,8,5).

What is the electron configuration of Al³⁺?

(2,8).

What is the electron configuration of K⁺?

(2,8,8).

What does the group number generally tell you for main-group elements in this booklet?

The number of valence electrons (e.g. group 1 has 1; group 13 has 3).

What does the period number tell you?

The number of occupied electron shells (e.g. period 3 has 3 shells).

What is an ion?

An atom or group of atoms that has gained or lost electrons and therefore has an overall charge.

How does an atom become a positive ion (cation)?

It loses one or more electrons, leaving more protons than electrons.

How does an atom become a negative ion (anion)?

It gains one or more electrons, giving it more electrons than protons.

Which type of elements typically form cations?

Metals, which typically lose their outer-shell electrons.

Which type of elements typically form anions?

Non-metals, which typically gain electrons to fill their outer shell.

Why does gaining or losing electrons give an atom a charge?

The numbers of positive protons and negative electrons are no longer equal.

How is an ion's charge written?

As a superscript after the element or ion symbol, e.g. Ca²⁺.

How do you calculate the number of electrons in a positive ion?

Electrons = atomic number − positive charge magnitude.

How do you calculate the number of electrons in a negative ion?

Electrons = atomic number + negative charge magnitude.

How many electrons does Al³⁺ have?

10 electrons (13 protons − 3).

How many electrons does O²⁻ have?

10 electrons (8 protons + 2).

How many electrons does Ca²⁺ have?

18 electrons (20 protons − 2).

How many electrons does Cl⁻ have?

18 electrons (17 protons + 1).

How do you identify whether a species is a cation or anion from proton and electron counts?

More protons than electrons = cation; more electrons than protons = anion; equal numbers = neutral.

What is metallic bonding?

The strong electrostatic attraction between positive metal cations and delocalised valence electrons.

Where does metallic bonding occur?

Between atoms in a metal.

What are delocalised electrons?

Valence electrons that are not attached to one particular atom and can move through the metal structure.

Give examples of metals with metallic bonding.

Sodium (Na), magnesium (Mg), copper (Cu) and gold (Au).

What is ionic bonding?

The strong electrostatic attraction between positive cations and negative anions in a three-dimensional lattice.

Which elements typically form ionic compounds?

A metal and a non-metal; ammonium compounds are an exception because ammonium is a polyatomic cation.

What happens to electrons when an ionic bond forms?

The metal transfers electrons to the non-metal; the metal becomes a cation and the non-metal becomes an anion.

Why do oppositely charged ions attract?

Opposite electrical charges attract through electrostatic forces.

What structure do ionic compounds form?

A three-dimensional crystal lattice of alternating positive and negative ions.

Give examples of ionic compounds.

NaCl, Mg(NO₃)₂ and CaCl₂.

What is covalent bonding?

Bonding in which non-metal atoms share electrons; attraction between the shared electrons and positive nuclei holds the atoms together.

Which elements form covalent compounds?

Non-metals combining with non-metals.

Why do non-metal atoms share electrons in covalent bonding?

Sharing allows atoms to fill their outer shells.

What can covalent bonding produce?

Molecules or giant covalent networks.

Give examples of covalent compounds.

CO₂, H₂O, NH₃ and Cl₂.

Which bonding type occurs between metal atoms?

Metallic bonding.

Which bonding type usually occurs between a metal and a non-metal?

Ionic bonding.

Which bonding type occurs between non-metal atoms?

Covalent bonding.

How well do metals conduct electricity, according to the booklet?

Very well.

Do solid ionic compounds conduct electricity according to the booklet?

No; the booklet states they can conduct when in solution.

Do covalent compounds conduct electricity according to the booklet?

Generally no.

What are the melting and boiling points of metallic substances generally like?

High.

What are the melting and boiling points of ionic compounds generally like?

High.

How do melting and boiling points vary among covalent substances?

High for network covalent substances, but low for molecular covalent substances.

What are typical mechanical properties of metals?

They are generally hard, ductile and malleable.

What is a typical property of ionic compounds when force is applied?

They are hard but brittle and can cleave.

What are typical hardness properties of covalent substances?

They can be hard or soft, depending on their structure.

What is lustre?

A shiny appearance; the booklet describes metals as shiny.