1.1 Model of The Atom, Symbols, Relative Atomic Mass, Electronic Charge & Isotopes

These flashcards are for Topic 1 - Atomic Structure & The Periodic Table in AQA GCSE Chemistry (Triple Higher). They cover specification points 4.1.1.1 - 4.1.1.7

What is the smallest part of an element that can exist?

An atom

Who first proposed in 1803 that all matter was made of tiny, indivisible spheres called atoms?

John Dalton

What subatomic particle did J. J. Thomson discover through his experiments?

The electron

The ____ __________ model of the atom, suggested by J.J. Thomson, describes the atom as a ball of positive charge with negative electrons embedded in it.

plum pudding

What experiment, designed by Ernest Rutherford in 1909, was used to test the plum pudding model?

The alpha particle scattering experiment

In the alpha scattering experiment, what were the positively charged alpha particles fired at?

A thin sheet of gold foil

What was the expected result of the alpha scattering experiment if the plum pudding model were correct?

All alpha particles were expected to pass straight through the foil.

What did the observation that most alpha particles passed straight through the gold foil indicate about the structure of an atom?

That an atom is mostly empty space.

What did the deflection of some alpha particles in Rutherford's experiment suggest about the atom's nucleus?

The nucleus must have a positive charge, as it repelled the positive alpha particles.

What did the observation that a small number of alpha particles bounced straight back from the gold foil imply?

That the mass of the atom is concentrated in a tiny central nucleus.

Rutherford's experiment led to the ________ model, which states the atom's mass is concentrated in a positively charged nucleus.

nuclear

Who adapted Rutherford's nuclear model by suggesting that electrons orbit the nucleus in specific shells or energy levels?

Niels Bohr

Further experiments by Rutherford led to the idea that the nucleus contained small, positively charged particles called what?

Protons

In 1932, who provided experimental evidence for the existence of neutrons in the nucleus?

James Chadwick

What two types of subatomic particles are found in the nucleus of an atom?

Protons and neutrons

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?

Very small

What is the relative charge of a proton?

+1

What is the relative charge of a neutron?

0

What is the relative charge of an electron?

-1

Why does an atom have no overall electrical charge?

It contains an equal number of positive protons and negative electrons, so their charges cancel out.

Where is most of the mass of an atom concentrated?

In its nucleus.

The radius of a nucleus is less than _________ of the radius of the atom.

1 / 10000th

What term describes the number of protons in the nucleus of an atom?

Atomic number

What is the term for the total number of protons and neutrons in an atom's nucleus?

Mass number

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

mass number - atomic number

A sodium atom has an atomic number of 11 and a mass number of 23. How many protons does it have?

11

A sodium atom has an atomic number of 11 and a mass number of 23. How many electrons does it have?

11

A sodium atom has an atomic number of 11 and a mass number of 23. How many neutrons does it have?

12

What is the definition of an isotope?

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

Isotopes of a given element have the same atomic number but different _____ numbers.

mass

Why do all isotopes of an element have the same chemical properties?

Because they have the same number of electrons, which determines chemical properties.

The isotope Hydrogen-1 (¹H) has how many protons, electrons, and neutrons?

1 proton, 1 electron, and 0 neutrons.

The isotope Hydrogen-2 (²H) has how many protons, electrons, and neutrons?

1 proton, 1 electron, and 1 neutron.

What is the definition of an ion?

An electrically charged particle formed when an atom or molecule gains or loses electrons.

How does an atom become a positive ion?

By losing electrons

Why does losing electrons cause an atom to become a positively charged ion?

Because it has more positively charged protons than negatively charged electrons, so it has an overall positive charge.

How does an atom become a negative ion?

By gaining electrons

Why does gaining electrons cause an atom to become a negatively charged ion?

Because it has more negatively charged electrons than positively charged protons, so it has an overall negative charge.

A sodium atom (Na) has 11 protons and 11 electrons. How many protons and electrons does a sodium ion (Na+) have?

11 protons and 10 electrons.

An oxygen atom (O) has 8 protons and 8 electrons. How many protons and electrons does an oxide ion (O2-) have?

8 protons and 10 electrons.

What is the term for the arrangement of electrons in shells or energy levels around the nucleus?

Electronic structure

What is the maximum number of electrons that can occupy the first electron shell?

2

For the first 20 elements, what is the maximum number of electrons that can occupy the second electron shell?

8

For the first 20 elements, what is the maximum number of electrons that can occupy the third electron shell?

8

What is the electronic structure of a sodium atom, which has 11 electrons?

2,8,1

What is the electronic structure of an argon atom, which has an atomic number of 18?

2,8,8

What is the electronic structure of a calcium atom, which has 20 electrons?

2,8,8,2

Why are the elements in Group 0 (the noble gases) chemically inert or unreactive?

Because they have a stable arrangement of electrons with a full outer shell.

Atoms react to achieve a stable electronic structure, which usually means having a _____ outer shell.

full

What is the definition of relative atomic mass (Ar)?

A weighted average mass of the atoms of an element, taking into account the abundance of its isotopes.

Why are relative atomic masses, like that of chlorine (35.5), often not whole numbers?

Because they are a weighted average of the masses of an element's different isotopes.

What is the formula to calculate the relative atomic mass (Ar) of an element with two isotopes?

A_r = ((abundance₁ × mass₁) + (abundance₂ × mass₂)) / total abundance (100)

Chlorine has two main isotopes: chlorine-35 (75% abundance) and chlorine-37 (25% abundance). Calculate its relative atomic mass.

35.5

Copper has two isotopes: copper-63 (69% abundance) and copper-65 (31% abundance). Calculate its relative atomic mass to one decimal place.

63.6

A substance made up of only one type of atom is called an ________.

element

A substance formed from two or more elements chemically combined in fixed proportions is called a ____________.

compound

The central part of an atom containing protons and neutrons is the __________.

nucleus

What is the name for the different energy levels in an atom that are occupied by electrons?

Electron shells

The number of electrons in the outermost shell of an atom determines its __________ properties.

chemical

A magnesium ion (Mg²⁺) is formed when a magnesium atom loses two electrons. If a Mg atom has 12 protons, how many electrons does the ion have?

10

This question is about elements, compounds and mixtures.

Substance A contains only one type of atom.

Substance A does not conduct electricity.

Which type of substance is A?

Non-metallic element

This question is about elements, compounds and mixtures.

Substance B contains two types of atoms.

The atoms are chemically combined together in fixed proportions.

Which type of substance is B?

Compound

What is the name of the elements in Group 0 of the periodic table?

Noble gases

Which statement about the elements in Group 0 is correct?

The boiling points increase down the group.

Neon is in Group 0.

What type of particles are in a sample of neon?

Atoms

The table shows the mass numbers and percentage abundances of the isotopes of gallium.

Calculate the relative atomic mass (A_r) of gallium.

Give your answer to 1 decimal place.

69.8

Gallium (Ga) is in Group 3 of the modern periodic table.

Give the numbers of electrons and neutrons in an atom of the isotope ⁶⁹₃₁Ga.

31 electrons and 38 neutrons

Gallium (Ga) is in Group 3 of the modern periodic table.

What is the most likely formula of a gallium ion?

Ga³⁺

This question is about models of the atom.

Atoms were first thought to be tiny spheres that could not be divided.

Which particle was discovered to change this model of the atom?

Electron

The diagram shows a model of the atom.

What is the name of this model of the atom?

Plum pudding mode

The model of the atom used today has three subatomic particles:

• electrons

• neutrons

• protons

Complete the sentences.

Atoms of the same element have the same atomic number because they have the same number of _______________.

Atoms of the same element can have different mass numbers because they have different numbers of _______________.

Atoms have no overall charge because they have the same number of _______________ and _______________.

protons, neutrons, protons, electrons

The radius of a nucleus is approximately 1 × 10^-14 m.

The radius of an atom is approximately 1 × 10^-10 m.

A teacher uses a ball of radius 1 cm to represent the nucleus.

What could represent the atom on the same scale?

A sports arena of radius 100 m.