Definitions Flashcards
What is matter?
What is mass of an object?
What is volume?
Matter is anything that takes up space e.g solid, liquid, gas
The mass of an object is the amount of matter it contains measured in kilograms (kg)
The volume is the amount of space that the matter takes up
Describe structure of solids
Solids retain a fixed shape
The particles are closely packed together in a regular structure and vibrate around a fixed position
Solids are not easily compressed
Describe liquids
Liquids take up the shape of the container that they occupy
•The particles are closely packed together, but there is no regular arrangement
•The particles can vibrate and move past each other
•Liquids are not easily compressed
Describe gases
Gases take up the shape of the container that they occupy
•The particles are spread out with no particular arrangement and can move freely
•Gases are easily compressed
What is the weight of an object?
The weight of an object is the force of gravity acting upon its mass
The weight of an object is expressed in newtons
What is force?
What equation is used for force?
Force is a push, a pull or other action that changes the motion of an object.
•It is equal to the mass of the object multiplied by the acceleration
•F = m x a
•Force is measured in Newtons
What is work?
Equation for work?
Work is an expression of the force applied to an object multiplied by the distance across to which it is applied
•W =Fxd
•Work is measured in joule (J)
What is energy?
The two types?
The ability to do work
•There are two types –
•Potential energy – energy that is stored
•Kinetic energy – energy being expended
Describe net charge?
Atoms that have the same number of protons and electrons will have no net charge
•The charges cancel each other out
Describe binding energy
The nucleus is held together by a strong nuclear force
•Creating a binding energy
•This is a measure of the amount of energy required to split the atom
What are the electron shells names?
What does n equal in 2n^2
K,L,M,N
N= number of the shell
What holds electrons in orbit?
What factors affect this?
Electrons are held in their orbits by binding energy
•This is dependent of several factors -
•How close the electron is to the nucleus
•How many protons there are in the nucleus
•The closer the electron is to the nucleus the stronger the binding energy
How can an electron be removed from its orbit?
An electron can be removed from its orbit if it is struck with an energy greater than the binding energy
What happens if ionisation occurs?
(X-ray production)
If this occurs in shell nearer the nucleus an electron from an outer shell will drop down to fill the inner shell vacancy
•Energy is released in the form of electromagnetic radiation – characteristic x-ray photons
•The orbit shells fill from the shell nearest the nucleus outwards as a vacancy in a shell makes it unstable
What happens when heat is given to an object?
When heat is given to an object, the particles within it are given kinetic energy
•Resulting in the particles moving more
•An object with a higher kinetic energy is described at a higher temperature than an object at a lower kinetic energy
Define temperature and heat
Temperature
Temperature, therefore, is a measure of hot or cold and is related to the average kinetic energy that the particles of an object have
Heat
Heat is the transfer of energy from one object of matter to another, or from one part of an object to another part
How does a heat transfer occur?
Heat transfer occurs because of a temperature gradient
•Occurs from an area of high temperature to an area of lower temperature.
•This transfer of energy continues until the temperatures of the two objects – or the parts of the same object – are the same
What is conduction?
The transfer of heat via direct molecular collision
•Results in a transfer of kinetic energy from higher to lower
•Conduction occurs in solids when there is a temperature gradient
What is convection?
The transfer of heat through liquids or gases
•The particles closest to the heat source are heated by conduction
•These particles expand and become less dense, causing them to rise
•As they rise, further particles are drawn in from the side towards the heat source and undergo the same process
As the particles rise, they bump into other particles and heat transfer occurs, again by the process of conduction
•This causes the particles to cool down and fall; they can then be reheated and go through the process of rising, cooling, and falling again (because of heat transfer) and convection currents are created
What is radiation?
The transfer of heat energy through waves
•As waves hit an object, kinetic energy is transferred to the object, causing an increase in temperature. This is how we feel in the heat from the sun
•Radiation is the only mechanism of heat transfer that can take place in a vacuum
What is electromagnetic radiation?
An electric and magnetic disturbance through space at the speed of light
•Eg radiowaves, x-ray gamma rays
•The electromagnetic spectrum is a way of ordering the different elect radiations
What is the same for all waves?
Define wavelength and frequency
Velocity
Wavelength - distance from one peak to another
•Frequency - number of cycles per second and in measured in Hertz (Hz)
What is non ionising radiation?
Low energy radiation with a longer wavelength
•E.g. Radio waves and microwaves
•Visible light is the only electromagnetic radiation visible to the naked eye
What is ionising radiation?
X-ray and gamma rays have the ability to ionize matter
•When a photon possesses sufficient energy it can remove an electron from an atom – ionisation
•When this occurs it causes damage to human tissue
Define element
Elements are substances that cannot be broken down into simpler substances
Define atomic number and atomic mass
The atomic number refers to the number of protons in the nucleus. It determines the chemical properties and defines the element. The atomic number is represented by the letter Z.
Atomic mass:
•The atomic mass is the combined number of protons and neutrons in the nucleus. It is represented by the letter A.
Define isotope
Isotopes are different forms of the same element.
•Their atoms have the same number of protons but a different number of neutrons
•Therefore, they have a different mass number
