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Atomic Structure. All substances are made up of atoms. Atoms have a radius of about 1 x 10-10 m The nucleus of the atom is 1/10000th the size of the whole atom, but contains most of the mass. The nucleus contains protons and neutrons. Protons have a positive charge, whilst neutrons are neutral, so the nucleus has a positive charge overall.
- The History of Atomic Structure. Scientific theories and models, based on experimental data, are used to understand the natural world. If new evidence contradicts established theories and models, they are changed or replaced.
- Changing Models. The accepted model of atomic structure has evolved over time, and the flowchart below represents the most important stages. Each model was for a time accepted as correct.
- Simple Atoms. The earliest concepts of atomic theory considered all matter to be made of small, indivisible, spherical atoms. These ideas began in Ancient Greece, but were fully adopted into Chemistry in the 1800’s.
- The “Plum Pudding” In this model, the atom is considered to be a solid sphere with a weakly positive charge. Negatively charged electrons are embedded into this solid sphere (like plums in a plum pudding – hence the name).
Atomic Structure Example Questions. Question 1: Name the components of the atom A, B and C from the diagram. [2 marks] GCSE Combined Science Foundation Combined Science Higher Physics Foundation Physics Higher AQA. Show Answer. Question 2: An oxygen nucleus contains 8 protons and 8 neutrons. What is the atomic number and mass number of this ...
On our dedicated atomic structure page you will find all the resources you require to revise the history of the atom and the development of the atomic model including electronic structure. Whether you are looking for AQA GCSE Chemistry revision materials for atomic structure or you are studying combined science, the worksheet and resources on this page will help.
3.1.1.2 - Mass Number and Isotopes. Mass number is represented using A and can be calculated as the sum of protons and neutrons in an atom. Atomic number is represented using Z and is equal to the number of protons in an atom. Using these, the quantity of each fundamental particle in an atom can be calculated. Example:
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1. What is an atom and why do we care about its structure? 2. Why has the model of the atom changed over time? 3. What are some practical implications of knowing the structure of the atom? First class
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1.1. A simple model of the atom, symbols, relative atomic mass, electronic charge and isotopes. 1.2. The periodic table. 1.3. Properties of transition metals.
