Atomic Structure & the Periodic Table

What is an atom? The smallest unit of an element.

What is a molecule? Two or more atoms chemically joined together.

What is an element? A substance made of only one type of atom.

What is a compound? A substance made of different elements chemically bonded together.

What are the three main subatomic particles? Protons, neutrons, electrons.

What is the charge of a proton? +1

What is the charge of a neutron? 0 (neutral)

What is the charge of an electron? -1

Where are protons found in an atom? In the nucleus.

Where are neutrons found in an atom? In the nucleus.

Where are electrons found in an atom? Orbiting in shells 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? 1/2000

What does the atomic number tell you? Number of protons in an atom.

What does the mass number tell you? Number of protons + neutrons.

How do you calculate number of neutrons? Mass number minus atomic number.

Why are atoms neutral? Equal number of protons and electrons (charges cancel).

What is an ion? An atom with a charge from losing or gaining electrons.

What are isotopes? Atoms of the same element with different numbers of neutrons.

What is the chemical symbol for sodium? Na

What is the symbol for magnesium? Mg

What is the symbol for chlorine? Cl

What is the symbol for oxygen? O

What does each row of the periodic table represent? A period – number of electron shells.

What does each column (group) represent on the periodic table? Same number of electrons in the outer shell.

What are Group 1 elements called? Alkali metals.

What are Group 7 elements called? Halogens.

What are Group 0 elements called? Noble gases.

What is unique about noble gases? Full outer shell of electrons (unreactive).

What is unique about alkali metals? Very reactive, one electron in outer shell.

What properties do alkali metals share? Soft, low density, react violently with water.

What happens when an alkali metal reacts with water? Produces hydrogen gas and a hydroxide.

Why do elements in the same group have similar reactions? They have the same number of electrons in the outer shell.

What trend is seen as you go down Group 1? Metals get more reactive.

Why do halogens have similar properties? Seven electrons in outer shell.

What trend is seen as you go down Group 7? Halogens get less reactive.

Why is chlorine more reactive than iodine? Easier to gain electrons in smaller atoms.

Who arranged the first periodic table? Dmitri Mendeleev.

How did Mendeleev arrange the periodic table? By atomic mass (weight) and left gaps for unknown elements.

What is the modern periodic table arranged by? Atomic number.

What is the difference between a metal and a non-metal? Metals conduct electricity; non-metals do not.

Where are metals found on the periodic table? On the left and centre.

Where are non-metals found? On the right.

Name one example of a transition metal. Iron (Fe)

What are transition metals? Metals found in the centre block of the table; variable valency.

What is the symbol for potassium? K

What is the symbol for iron? Fe

What is the relative atomic mass? Weighted average of isotope masses.

What is a chemical equation? Shows reactants and products of a reaction.

Why must equations be balanced? To conserve mass (atoms are not created or destroyed).

What is meant by electronic configuration? Arrangement of electrons in shells.

How many electrons in first shell? 2

How many electrons in second shell? 8

How many electrons in third shell? 8

If an atom has 6 electrons, what is its configuration? 2, 4

If sodium has atomic number 11, what is its configuration? 2, 8, 1

What charge does a sodium ion have? +1

What charge does a chloride ion have? -1

How does an atom become a positive ion? Loses electrons.

How does an atom become a negative ion? Gains electrons.

Name one physical property of Group 1 metals. Low melting point

Why do Group 1 elements get softer as you go down the group? More electron shells, weaker metallic bonding.

What happens when halogens react with alkali metals? They form salts.

What is formed when sodium reacts with chlorine? Sodium chloride (NaCl)

What type of bonding occurs between metals and non-metals? Ionic bonding

What type of bonding is found in metals? Metallic bonding

What is the electron configuration of a neon atom? 2, 8

What is a period trend in atomic radius? Atoms get smaller across a period.

What happens to reactivity in Group 1 as atomic number increases? Reactivity increases.

Describe a test for hydrogen gas. Lit splint 'pop' test.

Describe a test for oxygen gas. Glowing splint relights in oxygen.

What is the formula for relative atomic mass? (Isotope 1 x % abundance + isotope 2 x % abundance) / 100

How are alkali metals stored? Under oil – they react with air and water.

Why does lithium float on water? It's less dense than water.

Why is argon used in light bulbs? It's inert (unreactive).

What does inert mean? Unreactive.

Why do elements bond together? To achieve a full outer shell (stability).

Describe a chemical symbol. One or two letters representing an element.

Give two examples of diatomic molecules. H₂, O₂, N₂, Cl₂

What is a valency? The combining power of an atom.

What is the particle model? Explains properties of solids, liquids, gases.

What is a mixture? Combination of substances not chemically bonded.

How are mixtures separated? Physical methods (e.g. filtration, distillation).

Name three ways to separate mixtures. Filtration, distillation, chromatography.

What is filtration? Separates insoluble solids from liquids.

What is distillation? Separates liquids with different boiling points.

What is chromatography? Separates substances based on solubility and movement in a solvent.

Why are noble gases used in balloons? They are lighter than air, unreactive.

Name a use of helium. Airships, balloons.

What is the most abundant element in air? Nitrogen

Which Group contains the least reactive elements? Group 0 (noble gases)

Define atomic number. The number of protons in the nucleus of an atom.

Define mass number. The number of protons plus neutrons in an atom.

What is the formula for number of neutrons? Mass number minus atomic number.

If an atom has atomic number 6 and mass number 14, how many neutrons? 8

What does the chemical symbol 'C' stand for? Carbon

How do non-metals form ions? By gaining electrons.

How do metals form ions? By losing electrons.

Which element has configuration 2,8,7? Chlorine