Edexcel GCSE 9-1 Chemistry: SC3/4 - Atomic Structure and the Periodic Table

Paper 1 + 2 Specification: https://qualifications.pearson.com/content/dam/pdf/GCSE/Science/2016/Specification/GCSE_Chemistry_Spec.pdf

How has Dalton’s model of the atom differentiated over time?

Dalton's theory suggested that atoms are the smallest particles and cannot be divided. However, it is now known that atoms are made up of subatomic particles, such as protons, neutrons, and electrons

What is included in the structure of an atom? State their charges

• protons (+)

• neutrons (no charge)

• electrons (-)

• nucleus (no charge- balanced out)

Why do atoms contain equal numbers of protons and neutrons?

equal positive and negative charges result in a balanced overall charge as atoms do not have any charge

Why is the nucleus of an atom very small compared to the overall size of the atom?

since the force between the protons and neutrons in the nucleus is much stronger than the electrostatic repulsion in the protons, most of an atom is empty space

Where is most of the mass of an atom concentrated in?

in the nucleus

What is the mass number of an atom?

the total number of protons and neutrons in an atom

What do atoms of a given element have?

have the same number of protons in the nucleus and that this number is unique to that element

What do isotopes of a given element have?

different atoms of the same element containing the same number of protons but different numbers of neutrons in their nuclei

How come the relative atomic mass (A_r) for certain elements are not whole integers?

the existence of isotopes results in relative atomic masses of some elements not being whole numbers

How is relative atomic mass (A_r) calculated?

A_r = (mass*abundance)(mass*abundance) no. of isotopes basically / total abundance

How did Mendeleev arrange the elements at the time?

arranged the elements known at that time, in a periodic table by using properties of these elements and their compounds

What did his periodic table also predict?

to predict the existence and properties of some elements not then discovered

What is a fault within the arrangement of Mendeleev’s table?

Mendeleev thought he had arranged elements in order of increasing relative atomic mass but this was not always true because of the relative abundance of isotopes of some pairs of elements in the periodic table

What is the atomic number?

atomic number: the no. of protons in an atom’s nucleus; otherwise known as the proton number (symbol Z)

What are the elements in the present-day periodic table arranged by?

by order of increasing atomic number

How is the present-day periodic table arranged?

• elements are arranged in order of increasing atomic number, in rows called periods

• elements with similar properties are placed in the same vertical columns called groups

Identify elements as metals or non-metals according to their position in the periodic table, explaining this division in terms of the atomic structures of the elements

• non-metals are on the right of the table and the rest are metals

• non-metals tend to be less reactive

• metals have 1, 2 or 3 electrons in their outer shell (more spaces)

Predict the electronic configurations of the first 20 elements in the periodic table as diagrams and in the form, for example 2.8.1

have 2 electrons in first shell, 8 in next shell and so on

Explain how the electronic configuration of an element is related to its position in the periodic table

elements in the same period (down/column) have the same number of electrons in their outer shell and elements in the same group have the same number of shells

• 1 = +1

• 2 = +2

• 3 = +3

• 4 = ±4

• 5 = -3

• 6 = -2

• 7 = -1

• 8 or 0 = 0