Ionization energies
INTRODUCTION: The ionization energy of an atom measures how strongly an atom holds its electrons.The ionization energy is the minimum energy required to remove an electron from the ground state of the remote gaseous atom The first ionization energy, I1, is the energy needed to remove the first electron from the atom: i.e. the most loosely held electron! Na(g) -> Na+(g) + 1e- The second ionization energy, I2, is the energy needed to remove the next (i.e. the second) electron from the atom Na+(g) -> Na2+(g) + 1e- The higher the value of the ionization energy, the more difficult it is to remove the electron As electrons are removed, the positive charge from the nucleus remains unchanged, however, there is less repulsion between the remaining electrons INVESTIGATION: Periodic trends in ionization energies First ionization energies as a function of atomic number * 1.Within each period (row) the ionization energy typically increases with atomic number * 2.Within each group (column) the ionization energy typically decreases with increasing atomic number HYPOTHESIS: * Investigation 1: As the effective charge increases, or as the distance of the electron from the nucleus decreases, the greater the attraction between the nucleus and the electron. The effective charge increases across a period, in addition, the atomic radius decreases * Investigation 2: As we move
Determine the penetrating power and the range in air of the three radioactive emissions (Plutonium 239 for alpha, Strontium 90 for beta and Cobalt 60 for gamma).
Aim To determine the penetrating power and the range in air of the three radioactive emissions (Plutonium 239 for alpha, Strontium 90 for beta and Cobalt 60 for gamma). Method 1 The apparatus were set up as in the diagram below to measure the range in air up to 50 cm for each source. Before the experiment took place the background radiation was measured as 80 counts in 5 minutes therefore 16 counts per minute. Experimental precautions were: The radioactive source is aligned with a ruler to the GM tube as accurately as possible so that the maximum radiation is measured A set square was used to measure the exact point at which the source and tube were placed The counter was reset each time so the counter read zero so this would reduce zero error in the experiment and the hold button was pressed to freeze the measurement Thirty seconds were left between the start of the count and the recording so the reading would be less instantaneous and more reliable Everything was kept constant for all three experiments and the counts were recorded at regular intervals of 5 cm. Safety precautions included removing the sources from a secure wooden box using thongs and tweezers and placed in plasticene, the set square was held using thongs and all those carrying out the experiment stood behind the source to minimise any direct radiation exposure. Method 2 The equipment was set up
Experiment Report: Studying a simple harmonic oscillator.
Name: Yu Wai So (19) 6S Experiment Report: Studying a simple harmonic oscillator Objective The simple harmonic motion of a pendulum can be studied by attaching a ticker-tape to a pendulum bob and analyzing the dots marked on the tape. Theory In this experiment, a string was used to suspend a 0.5 kg mass. Refer to the diagram above, Considering the tangential force on the mass, ?The oscillation is simple harmonic. Therefore, we can find out more on simple harmonic motion by analyzing the ticker-tape we obtained after the experiment. Apparatus . 0.5 kg ringed mass 2. 1.5 m length of string 3. Ticker-tape timer 4. Ticker-tape 5. Low voltage power supply (a.c.) 6. Retort stand and clamp Procedure . The apparatus as shown in the figure was set up. A pendulum was suspend by a string and was attached to a retort stand and clamp. A ticker- tape was attached to the mass and was inserted to the ticker-tape timer. The mass was pulled to one side. The timer was switched on and the mass was allowed to swing to the other side. 2. After the pendulum reached its highest position, the ticker-tape timer was switched off and the ticker-tape was detached from the mass. The dots marked on the tape were examined. During the oscillation, the pendulum bob accelerated and then decelerated when it was approaching its highest position. The acceleration of the bob was always
An investigation into the effect of temperature on a squash ball
An investigation into the effect of temperature on a squash ball For my experiment I will be using a blue spotted squash ball. This is because the blue spotted ones are designed to have the most bounciness. This is will make it a lot easier to judge the height of the ball's bounce making my experiment more accurate. I'll set up my equipment to the diagram below. Then I'll put the squash ball in a beaker and then put the beaker in a water bath. The water will obviously be heated with a Bunsen burner which will then heat the ball up. I've chosen this method so the ball doesn't get wet, and the experiment is fair. I will then drop the ball from a height of 2 meters. It will be landing onto a piece of MDF (Medium Density Fibreboard) to make sure the surface won't affect my results, so it's more of a fair test. To judge how high the ball has bounced, I will be using my eyesight. Diagram Equipment list 4 different coloured squash balls Beaker Water bath 2, 1 meter rulers MDF Kettle Ice Thermometer Stopwatch Tongs I did a preliminary experiment to see if my method would work and if there were any problems with the way I will conduct my experiment. Preliminary Results Temperature (ºC) Distanced Bounced (Cm) 90 81 40 68 0 20 Factors affecting my experiment * If I use different squash balls of different elasticity it will affect the bounciness of the
Thermal insulators.
Zeadon Jamil Thermal insulators Aim To investigate different materials for the most effective thermal insulator for a house. Introduction Heat transfer is the gain and loss of energy. There are three ways in which thermal energy can be transferred: * Conduction * Convection * Radiation Conduction - this is when energy travels from molecule to another. When one molecule receives energy it begins to vibrate and hits other molecules and makes them vibrate. And will spread throughout the object. Convection - this will only occur in gases and liquids. When heat is applied to the bottom of the substance, it will heat it up. When it heats up, it will rise to the top, forcing colder areas towards the heat source and then they will receive energy and rise to the top, etc. Radiation - it travels in waves. When it hits a molecule it makes it vibrate. I will be concentrating on conduction, as this is the main way in which thermal energy is transferred lost from housing. Which means that I need something that is a bad thermal conductor (good thermal insulator) to keep the amount of conduction to a bare minimum? Plan I am planning to test five materials (paper, cling film, cloth, bubble wrap and plastic) and one control, three times and find the average (to ensure accuracy). Whichever material changes the temp of the water the least is the best insulator. I will wrap
What causes feedback in a guitar or microphone?
What causes feedback in a guitar or microphone? Just for the record, feedback is actually the mechanism used to control almost every electronic device manufactured. Stability is a critical issue for all of these feedback control systems, and the gain, or level of amplification, used is a critical element in their design. When musicians talk about feedback, however, the connotation is negative because it is the term they use to describe the shreek that results when the gain is too high on the output of an amplified instrument or microphone. There are several potential mechanisms by which feedback can occur when sound is amplified. Let's deal first with the simple case of a microphone and an amplified speaker. (See the figure, but ignore the guitar for now.) Feedback occurs when a "loop" between an input and output is closed. In this scenario, the microphone serves as the input and the amplified speaker provides the output. In our example, the loop between the input and output closes when the sound radiated from the amplified speaker reaches the microphone and is subsequently amplified again. In effect, the cat is chasing its tail. (See the dashed red line connecting the loudspeaker to the microphone through acoustic feedback in the figure.) Gain is an important factor in this instance; it also explains why equalizers are frequently employed to control acoustic feedback. The
The factors affecting the resistance of a metalic conductor.
INVESTIGATION: THE FACTORS AFFECTING THE RESISTANCE OF A METALLIC CONDUCTOR Metals conduct electricity because the electrons in the metal can move about inside the structure. These electrons are called free electrons. Electricity is conducted through a conductor by means of free electrons. Atoms consist of protons, electrons and neutrons. The protons and neutrons make the nucleus of an atom while the electrons circle the outer area of the atom. Electrons in metal are able to move freely and are used as current in an electric circuit. This is because they carry a charge and can move all around the circuit with this charge. While these electrons are travelling around the circuit, atoms are sometimes in the way, causing the two to collide. This takes out some of the energy from the electron and transfers it to the atom. This is how resistance occurs. The number of free electrons depends on the material and the more the free electrons in a substance the better the material as a conductor. All conductors offer resistance to the flow of current. The conductor's atoms determine this resistance. For example copper atoms offer negligible resistance to an electric current because a significant proportion of its electrons are free to move from electron to electron. Thus copper is commonly used as a conductor. Current, is the flow of electrons around a circuit. Those materials,
Resistivity Coursework
Resistivity Coursework Theory suggests that the resistance of a wire is found with this formula: R=?L/A R = Resistance ? = Resistivity of wire L = length of wire A = cross-sectional area I will now perform an investigation to confirm the legitimacy of this formula and confirm a value for ? in a Nichrome wire. Planning A4c: Fully labelled Diagram A4d, A6d: Comprehensive list of Apparatus including Instrument Ranges Variable power supply unit Analogue ammeter, accuracy 0.01A, range 0 to 1.0A Analogue Voltmeter, accuracy 0.1V, range 0 to 5V Copper leads x5 Crocodile clip x2 Nichrome Wire (diameter=4.57 x 10-4m) Ruler, accuracy 0.001m, range 0 to 1.000m A2c: Safety Confirm the Initial power supply is at 0 volts other wise huge voltages will most likely cause unnecessary heating in wires including the Nichrome not only a hazard but may compromise my readings. Make sure my practical investigation is free of all or any obstructions; any unnecessary wires may cause a short circuit leading to damaging the power supply unit, ammeters and voltmeters. A4b, A6a: Identifying Variables and Constants The variables in this investigation are voltage (V), resistance (R) and length of Nichrome wire (L). Resistance and length are directly proportional to each other. Constants are current (I), cross sectional area of wire (A) Resistivity (?) and temperature of the Nichrome
I aim to find out if the mass of an object affects the speed at which it falls.
Falling Objects Plan I aim to find out if the mass of an object affects the speed at which it falls. I predict that the mass will not alter the speed, as it will reach terminal velocity. I think that all the results will stay roughly the same even though I have changed the mass. When something falls, its potential energy is changed into kinetic energy. Therefore the only thing in this experiment that could alter the speed at which it falls is the air resistance and the height. (These would change the time at which the object is in the air). Theoretically, as I am keeping these the same, the speed should not change. The scientist Galileo proved this. This is a quote taken from the Galileo Timeline. (http://es.rice.edu/ES/humsoc/galileo/galileo_timeline.html) "1589-1592 Teaches mathematical subjects at the University of Pisa (salary 160 scudi per year). Some tracts--lecture notes--written during this period have survived. In On motion Galileo uses the Archimedian approach to motion: the speed of falling bodies is proportional to their density, not their weight as Aristotle had maintained. According to Vincenzo Viviani Galileo demonstrated his conclusions by dropping weights from the leaning tower of Pisa." I will drop the object, which will be a small container, from a height of 30cm. I will measure the speed of the object using a light gate, which will make my results
An Investigation Into The Resistance Of Conductive Putty
An Investigation Into The Resistance Of Conductive Putty Primary Work In this experiment I will be using conductive putty for the first time. I do have knowledge of electrical circuits such as parallel and series. I have knowledge of electrical equipment like bulbs, battery cells and variable resistors. And I have knowledge of the circuits' advantages and disadvantages. My plan is to use the putty in a series circuit with an ammeter and record the currant. Prediction I believe that the shorter the piece of putty the stronger the currant will be. I believe this because I have found that electrons always take the shortest route. Apparatus In this experiment I will need; a light bulb, a light bulb holder, a battery pack, four crocodile clips, an ammeter, a power supply, a piece of putty and four wires. I will need the light bulb to show if the circuit is complete. The battery pack is control the electrical currant and the crocodile clip and wire to carry the currant. Safety The first danger is the power of the electrical currant. To prevent any danger of electrical shocks I will use the battery pack to control the strength of the currant and turn it down to four cells. The power will be DC (direct currant) and the putty used will be on a non-conductive surface. What factors could affect what happens There are two obvious factors what come to mind and that is
