EDEXCEL IGCSE CHEMISTRY: DOUBLE SCIENCE 复习笔记:1.3.1 Atoms: Definitions & Structure

EDEXCEL IGCSE CHEMISTRY: DOUBLE SCIENCE 复习笔记:1.3.1 Atoms: Definitions & Structure

Atoms & Molecules

 

  • It is important to understand the terms atom and molecule when referring to atomic structure, elements and compounds

 

Atoms & Molecules Definitions Table

 

1.3.1-Atoms-_-Molecules-Definitions-Table

 

The Structure of the Atom

 

  • Elements are made of tiny particles of matter called atoms
  • Each atom is made of subatomic particles called protonsneutrons and electrons
  • Their size is so tiny that we can't really compare their masses in conventional units such as kilograms or grams, so a unit called the relative atomic mass is used
  • One relative atomic mass unit is equal to one twelfth the mass of a carbon-12 atom.
  • All other elements are measured relative to the mass of a carbon-12 atom and since these are ratios, the relative atomic mass has no units
  • Hydrogen for example has a relative atomic mass of 1, meaning that 12 atoms of hydrogen would have exactly the same mass as 1 atom of carbon
  • The relative mass and charge of the subatomic particles are shown below:

 

The Mass & Charge of Subatomic Particles Table

 

3.1.1-Atomic-Structure-the-Periodic-Table-table 

Exam Tip

The mass of an electron can just be stated as 'negligible' or 'very small' in an exam. You do not need to learn the value.

Key Terms

 

  • You need to know the following terms to describe the properties and characteristics of atoms

 

Atomic Structure Key Terms Table

 

1.3.1-Atomic-Structure-Key-Terms_1

 

Exam Tip

The term nucleon number is an alternative to mass number and means the same thing. A nucleon is a collective name for protons and neutrons.

转载自savemyexams

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