CIE A Level Chemistry: Atomic Structure and Subatomic Particles (Chapter 1)

Atom

Smallest part of an element involved in reactions.

Nucleus

Dense core of an atom containing protons and neutrons.

Proton

Positively charged subatomic particle in the nucleus.

Neutron

Neutral subatomic particle found in the nucleus.

Electron

Negatively charged particle orbiting the nucleus.

Relative Atomic Mass

Mass of particles compared to each other.

Relative Charge

Charge of particles compared to each other.

Mass Number

Total number of protons and neutrons in nucleus.

Atomic Number

Number of protons in an atom's nucleus.

Ions

Charged particles formed by gaining or losing electrons.

Electrostatic Attraction

Force holding electrons around the positively charged nucleus.

Deflection in Electric Field

Behavior of particles in an electric field.

Neutron Behavior

Neutrons are unaffected by electric fields.

Electron Behavior

Electrons are easily deflected towards positive plates.

Proton Behavior

Protons deflect towards negative plates, less than electrons.

Nucleons

Collective term for protons and neutrons.

Charge of Electron

Charge is -1.602 x 10^-19 coulombs.

Charge of Proton

Charge is +1.602 x 10^-19 coulombs.

Mass of Electron

Negligible compared to protons and neutrons.

Atomic Structure

Arrangement of protons, neutrons, and electrons.

Number of Neutrons

Calculated as mass number minus atomic number.

Mass Concentration

Most mass is in the nucleus of an atom.

Electron Cloud

Region of negative charge around the nucleus.

Relative Mass of Proton

Assigned a relative mass of 1.

Relative Mass of Neutron

Assigned a relative mass of 1.

Relative Mass of Electron

Mass is 1/1836 of proton/neutron.

Protons

Positively charged particles in an atomic nucleus.

Electrons

Negatively charged particles orbiting the nucleus.

Neutrons

Neutral particles in an atomic nucleus.

Ion

Atom with a net electric charge due to loss/gain of electrons.

Cation

Positively charged ion formed by losing electrons.

Anion

Negatively charged ion formed by gaining electrons.

Atomic Radius

Half the distance between two bonded nuclei.

Ionic Radius

Size of an ion compared to its neutral atom.

Electron Shell Theory

Explains electron arrangement and atomic size trends.

Shielding Effect

Inner electrons repel outer electrons, affecting size.

Trends Across Period

Atomic radius decreases due to increasing nuclear charge.

Trends Down Group

Atomic radius increases due to additional electron shells.

Formula for Protons

Protons = Mass number - Neutrons.

Formula for Neutrons

Neutrons = Mass number - Protons.

Neutral Atom

Atom with equal numbers of protons and electrons.

Increasing Negative Charge

Causes ionic radius to increase.

Increasing Positive Charge

Causes ionic radius to decrease.

Atomic Radius Patterns

Decreases across periods, increases down groups.

Nuclear Charge

Positive charge of the nucleus affecting electron attraction.

Electrostatic Force

Attraction between charged particles in an atom.