Elements in the periodic table are arranged in order of increasing...

Atomic number

Why do elements in the same group have similar chemical properties?

Same number of outer-shell electrons

What do the seven 'diatomic elements' have in common?

They exist naturally as X₂ molecules

What charge and location does a proton have?

1+, inside nucleus

How do you calculate the number of neutrons in an atom?

Mass number − atomic number

Isotopes of the same element have the same number of protons but different...

Number of neutrons

How does a metal atom typically form an ion?

By losing electrons

Why do atoms form bonds?

To achieve a full outer shell / be more stable

A compound formed between a metal and a non-metal is...

Ionic

Compounds ending in '-ide' typically contain...

Only two elements

A covalent bond is best described as...

Mutual attraction of two nuclei for a shared pair of electrons

What shape is a water molecule (H₂O)?

Angular (bent)

Why do covalent molecular substances have low melting/boiling points?

Only weak forces between molecules need breaking

How many covalent bonds does each carbon atom form in diamond?

4

Why does graphite conduct electricity while diamond doesn't?

Graphite has delocalised electrons free to move; diamond's electrons are all used in bonds

An ionic bond is best described as...

Electrostatic attraction between a positive and negative ion

Why don't solid ionic compounds conduct electricity?

The ions are fixed in place in the lattice, not free to move

What happens when an ionic compound dissolves in water?

The lattice breaks up and ions are surrounded by water molecules, becoming free to move

A substance melts at −35°C and boils at 150°C. What state is it at room temperature (~20°C)?

Liquid

Elements in the periodic table are arranged in order of increasing what?

Atomic number

Why do elements in the same group have similar chemical properties?

They have the same number of outer-shell (valence) electrons

What are Group 1 elements called?

Alkali metals

What are Group 7 elements called?

Halogens

What are Group 0 elements called, and why are they unreactive?

Noble gases

What does the period (row) number tell you about an atom?

The number of electron shells it has

What are the "7 diatomic elements" and what do they have in common?

H2, N2, O2, F2, Cl2, Br2, I2

How does reactivity change down Group 1 (alkali metals)?

Reactivity increases down the group

What charge and mass does a proton have?

1+ charge, mass of 1

What charge and mass does a neutron have?

0 charge, mass of 1

What charge and mass does an electron have?

1- charge, negligible mass (~0)

Why are atoms overall neutral?

Because the number of protons (+) equals the number of electrons (-)

What did Rutherford's gold foil experiment show?

Atoms are mostly empty space with a small, dense, positively charged nucleus

In nuclide notation, what does the atomic number tell you?

The number of protons

In nuclide notation, what does the mass number tell you?

The total number of protons + neutrons

How do you calculate the number of neutrons in an atom?

Mass number minus atomic number

What are isotopes?

Atoms of the same element (same atomic number) with a different mass number (different number of neutrons)

Do isotopes have the same or different chemical properties?

Same chemical properties (same electron arrangement), but different physical properties (different mass)

What is an ion?

A particle that has lost or gained electrons

How do metal atoms typically form ions?

By losing electrons, forming positive ions

How do non-metal atoms typically form ions?

By gaining electrons, forming negative ions

How are electrons arranged around the nucleus?

In energy levels (shells), filled from the inside out (2, 8, 8...)

An atom has the electron arrangement 2,8,7. Which group is it in?

Group 7

Why do atoms form bonds?

To achieve a full outer shell like the noble gases — this makes them more stable / lower energy

What type of compound forms between a metal and a non-metal?

Ionic

What type of compound forms between two non-metals?

Covalent

What does a compound name ending in "-ide" tell you?

It contains only two elements (e.g. sodium chloride)

What does a compound name ending in "-ite" or "-ate" tell you?

It contains three elements, one of which is oxygen (e.g. sulfate, carbonate)

What is a covalent bond?

Two atoms held together by their shared attraction to a shared pair of electrons

What is a single covalent bond vs a double covalent bond?

Single = 1 shared pair of electrons (e.g. H-H); double = 2 shared pairs (e.g. O=O)

What is the structure of a covalent molecular substance?

Small, separate molecules held together by weak van der Waals forces between molecules

What is the structure of a covalent network substance?

One giant 3D lattice of atoms, with strong covalent bonds throughout — no separate molecules

Why do covalent molecular substances have low melting/boiling points?

Only the weak van der Waals forces between molecules need to be broken, not the strong covalent bonds within them

Why do covalent network substances have high melting/boiling points?

Many strong covalent bonds throughout the lattice must be broken

Give examples of covalent molecular substances

H2O, CO2, Cl2, CH4

Give examples of covalent network substances

Diamond, graphite, silicon, boron

How many covalent bonds does each carbon atom form in diamond, and what structure does this give?

4 bonds — a rigid 3D tetrahedral network

How many covalent bonds does each carbon atom form in graphite, and what structure does this give?

3 bonds — flat layers, with weak forces between layers letting them slide

Why does graphite conduct electricity but diamond doesn't?

Graphite has one delocalised electron per carbon free to move; diamond uses all electrons in bonds, so none are free

What determines the shape of a molecule?

The number of bonded pairs and lone pairs around the central atom (electron pairs repel and spread as far apart as possible)

What shape is a molecule with 2 bonded pairs and no lone pairs (e.g. HCl)?

Linear

What shape is a molecule with 2 bonded pairs and 2 lone pairs (e.g. H2O)?

Angular (bent) — lone pairs repel more, giving a smaller bond angle

What shape is a molecule with 3 bonded pairs and 1 lone pair (e.g. NH3)?

Trigonal pyramidal

What shape is a molecule with 4 bonded pairs and no lone pairs (e.g. CH4)?

Tetrahedral

How can you predict molecule shape using group numbers?

Compare the central atom's group to a known example — e.g. S is in the same group as O, so H2S is angular like H2O

If melting point is above room temperature, what state is the substance at room temperature?

Solid

If melting point is below room temperature but boiling point is above it, what state is the substance at room temperature?

Liquid

If both melting point and boiling point are below room temperature, what state is the substance at room temperature?

Gas

What is an ionic bond?

The electrostatic attraction between a positive ion and a negative ion

How is an ionic bond formed?

By the transfer of electrons from a metal atom to a non-metal atom

What is the structure of an ionic compound?

A giant ionic lattice — a regular 3D pattern of alternating positive and negative ions

Why do ionic compounds have high melting and boiling points?

There are many strong ionic bonds (electrostatic forces) throughout the lattice that need to be broken

Do solid ionic compounds conduct electricity? Why or why not?

No — the ions are fixed in place in the lattice and not free to move

Do molten or dissolved ionic compounds conduct electricity? Why?

Yes — the lattice breaks down and the ions are free to move

What happens when an ionic compound dissolves in water?

The lattice breaks apart and water molecules surround and separate the ions

Do covalent molecular substances (like H2O, CO2) conduct electricity as solids or liquids?

No — no free ions or delocalised electrons

Does graphite conduct electricity as a solid?

Yes — due to delocalised electrons (the exception among covalent substances)

Do metals conduct electricity as solids and liquids?

Yes, in both states — delocalised electrons are always free to move

What is a metallic bond?

A lattice of positive ions surrounded by a "sea" of delocalised electrons, held by electrostatic attraction

Why do metals conduct electricity?

They have delocalised electrons that are free to move and carry charge

Why are metals malleable and ductile?

The layers of positive ions can slide over each other while staying held by the sea of delocalised electrons

What's the difference between atomic number and mass number?

Atomic number = number of protons; mass number = number of protons + neutrons

What's an easy way to remember why ionic compounds only conduct when molten/dissolved, not solid?

Solid = ions locked in lattice, can't move; molten/dissolved = lattice breaks, ions move freely