Atomic Structure retrieval questions

Question 1

What is an atom?

Answer 1

Smallest part of an element that can exist

Atoms are the building blocks of matter.

Question 2

What is Dalton’s model of the atom?

Answer 2

Atoms as solid spheres that could not be divided into smaller parts

This model was one of the earliest to describe atomic structure.

Question 3

What is the plum pudding model of the atom?

Answer 3

Sphere of positive charge with negative electrons embedded in it

Proposed by J.J. Thomson, this model suggested that electrons were distributed throughout a positively charged sphere.

Question 4

What did scientists discover in the alpha scattering experiment?

Answer 4

Some alpha particles were deflected by the gold foil, showing that an atom’s mass and positive charge must be concentrated in one small space (the nucleus)

This experiment was conducted by Ernest Rutherford.

Question 5

Describe the nuclear model of the atom.

Answer 5

Dense nucleus with electrons orbiting it

This model replaced the plum pudding model and introduced the concept of a central nucleus.

Question 6

What did Niels Bohr discover?

Answer 6

Electrons orbit in fixed energy levels (shells)

Bohr’s model added quantized energy levels to the atomic structure.

Question 7

What did James Chadwick discover?

Answer 7

Uncharged particle called the neutron

Chadwick’s discovery of the neutron helped explain atomic mass.

Question 8

Where are protons and neutrons located?

Answer 8

In the nucleus

Protons and neutrons are found at the center of the atom.

Question 9

What is the relative mass of each sub-atomic particle?

Answer 9

Proton: 1, Neutron: 1, Electron: 0 (very small)

The mass of electrons is negligible compared to protons and neutrons.

Question 10

What is the relative charge of each sub-atomic particle?

Answer 10

Proton: +1, Neutron: 0, Electron: -1

The charges of protons and electrons are equal in magnitude but opposite in sign.

Question 11

How can you find out the number of protons in an atom?

Answer 11

The atomic number on the Periodic Table

The atomic number uniquely identifies an element.

Question 12

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

Answer 12

Mass number - atomic number

The mass number is the total number of protons and neutrons.

Question 13

Why do atoms have no overall charge?

Answer 13

Equal numbers of positive protons and negative electrons

This balance of charge results in a neutral atom.

Question 14

How many electrons would you place in the first, second, and third shells?

Answer 14

Up to 2 in the first shell and up to 8 in the second and third shells

This is based on the electron configuration rules.

Question 15

What is an element?

Answer 15

Substance made of one type of atom

Elements are pure substances that cannot be broken down into simpler substances by chemical means.

Question 16

What is a compound?

Answer 16

Substance made of more than one type of atom chemically joined together

Compounds have unique properties different from their constituent elements.

Question 17

What is a mixture?

Answer 17

Two or more substances not chemically combined

Mixtures can be separated by physical means.

Question 18

What are isotopes?

Answer 18

Atoms of the same element (same number of protons) with different numbers of neutrons

Isotopes can have different physical properties due to their mass differences.

Question 19

What are the four physical processes that can be used to separate mixtures?

Answer 19

Filtration, crystallisation, distillation, fractional distillation, chromatography

Each method exploits different physical properties of the components in the mixture.

Question 20

What is relative mass?

Answer 20

The average mass of all the atoms of an element

Relative mass is often expressed in atomic mass units (amu).