AQA GCSE Chemistry (Triple) - Atomic Structure and the Periodic Table

These flashcards cover key concepts from AQA GCSE Chemistry, focusing on atomic structure and the periodic table.

What is the structure of an atom?

An atom has a nucleus containing protons and neutrons, surrounded by electrons in energy levels (shells).

What charge does the nucleus of an atom have?

Positive, because it contains protons.

Why do atoms have no overall charge?

Because they contain equal numbers of protons (+1) and electrons (–1).

What are isotopes?

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

What is the relative atomic mass (Ar) of lithium with 7.5% Li-6 and 92.5% Li-7?

Ar = (6×7.5 + 7×92.5)/100 = 6.9.

How has the model of the atom changed over time?

Dalton → Thomson → Rutherford → Bohr → Chadwick (neutrons).

What did Rutherford's experiment reveal about the atom's structure?

A few alpha particles were deflected or bounced back, indicating a small, dense, positively charged nucleus.

What is the maximum number of electrons in the first, second, and third shells?

2 in the first shell, 8 in the second shell, and 8 in the third shell.

What is the electronic structure of oxygen?

Oxygen: 2,6.

What is the electronic structure of sodium?

Sodium: 2,8,1.

Why are noble gases unreactive?

They have full outer electron shells, making them stable.

How are elements arranged in the modern periodic table?

In order of increasing atomic number.

What do groups represent in the periodic table?

Groups represent outer electrons.

What do periods represent in the periodic table?

Periods represent electron shells.

Why did Mendeleev leave gaps in his periodic table?

To allow for undiscovered elements with similar properties.

What are three properties of metals?

Good conductors, malleable, high melting points.

Why do metals form positive ions?

They lose electrons to achieve a full outer shell.

Why do non-metals form negative ions?

They gain electrons to achieve a full outer shell.

Describe the reaction of alkali metals with water.

Fizzing, hydrogen gas released, alkaline solution formed.

Write a balanced equation for sodium reacting with water.

2Na + 2H2O → 2NaOH + H2.

Why does reactivity increase down Group 1?

Outer electrons are further from the nucleus and less strongly attracted.

What are the states and colours of Cl, Br, and I?

Cl: green gas, Br: red-brown liquid, I: grey solid (purple vapour).

Why does reactivity decrease down Group 7?

Gaining an electron becomes harder due to shielding and distance from the nucleus.

Give an example of a halogen displacement reaction.

Cl2 + 2KBr → 2KCl + Br2.

What are the trends in Group 0?

Boiling points and density increase down the group.

Why are noble gases used in light bulbs?

They are inert and do not react with the filament.