7 Ions and ionic bonding This section returns to bonding – the way in which atoms are joined to each other. You have already met one type of bonding involving covalent bonds, which is found in molecules. However, this is not the only bonding found in compounds. In this section you will look at ionic bonding and the ionic compounds that contain such bonding. What is the main difference between the covalent compounds you met in Author(s):
6.3 Chemical formulas By using symbols, elements can be represented much more conveniently and much more briefly. This method of using symbols can be extended to compounds. You will now look further into this idea using a very familiar compound: water. Recall which atoms there are in a water molecule. 2.6.1 (a) Using Lego as a model In this kind of building set, there are a limited number of types of block and each block has a particular shape. Just as importantly, each one has a particular way in which it can link to other blocks because of the way the studs are arranged. The blocks can help you see how the atoms link in a molecule of water. Look at Figure 7 where the red brick represents an oxygen atom and the white bricks represent hydrogen atoms. There are only two locations where the hydrogen atoms can join th 5 Questions and answers Define each of the following: grammar, phonology, syntax, semantics, noun, verb, subject, object. Grammar: The set of unconscious rules or pr Learning outcomes By the end of this unit you should be able to: recognise definitions and applications of each of the terms printed in bold in the text; understand and apply basic grammatical terminology; describe briefly the different types of sounds used in speech in both acoustic and articulatory terms; outline the key features of human language as compared to the vocalisations of other species; describe the complex psychologi Introduction This unit is an adapted extract from the course Biological psychology: exploring the brain (SD226) This unit looks at how language is understood, which includes hearing and how sounds and words are interpreted by the brain. It takes an interdisciplinary approach and should be of wide general interest. 9 Sedimentation at the end of the Caledonian Orgeny; Section 10 Legacy The document attached below includes the ninth and tenth sections of Mountain building in Scotland, as well as the index. In these sections, you will find the following subsections: 9.1 Introduction 9.2 The Old Red Sandstone and the Devonian Period 9.3 Distribution and stratigraphy of the Late Silurian to Devonian Basins 9.4 Sedimentation and tectonics in the Midland Valley 8 Multiple plate collisions and the end of the Iapetus Ocean The document attached below includes the eighth section of Mountain building in Scotland. In this section, you will find the following subsections: 8.1 Introduction 8.2 Palaeocontinental reconstructions 8.2.1 The global view 8.2.2 A model for the closure of the Iapetus Ocean 8.2.3 Summary of Section 8.2 8.3 Tectonics of the Northe Learning outcomes When you have studied this unit you should be able to: describe the geological history of the Scottish Highlands; give examples of igneous, metamorphic and structurally complex rocks. Acknowledgements Except for third party materials and otherwise stated (see terms and conditions), this content is made available under a Creative Commons Attribution-NonCommercial-ShareAlike 2.0 Licence Grateful acknowledgement is made to the following sources for permission to reproduce material in this unit: 12.7 Summary of Section 12 For precise localisation of a sound source, binaural cues are required. Two types of binaural cue are used to localise non-continuous sounds in the horizontal plane: interaural time differences, which are most efficient for low-frequency sounds (20–1500 Hz) and interaural intensity cues, which are important for high-frequency sounds (1500–20 000 Hz). The frequency responses in the superior olive reflect these differences. The medial superior olive includes neurons that are responsiv 12.6 Distance cues There are two main cues available that allow us to judge the distance to a sound source. The first of these is the sound pressure level. Sound pressure level drops by 6 dB each time the distance that a sound travels doubles. In other words, if the sound pressure level of a sound is 60 dB SPL when its source is 1 m from you, then it will be 54 dB SPL if you move back another metre so that you are now 2 m away from its source. Therefore lower sound pressure levels indicate a greater distance. A 12.4 Interaural intensity differences The brain has another process for localizing high-frequency sounds (above 1500 Hz): interaural intensity differences. Where does processing of interaural intensity differences take place? 12.3 Interaural time delays: continuous tones Coincidence detectors and delay lines cannot be used to localise a continuous tone. Why? Because, a continuous tone is always present at both ears and if we 12.2 Interaural time delays: non-continuous sounds The average distance between human ears is about 20 cm. Therefore, if a sudden noise comes at you from the right, perpendicular to your head, it will reach your right ear 0.6 ms before it reaches your left ear. For a sound coming from directly in front of you there will be no delay, and at angles between, the delay will be between 0 and 0.6 ms. Therefore there is a simple relationship between the location of the sound source and the interaural delay. It is this delay that enables us to locali 12.1 Localisation of sound in the horizontal plane While information about frequency and intensity is essential for interpreting sounds in our environment, sound localisation can be of critical importance for survival. For example, if you carelessly cross the street, your localisation of a car's horn may be all that saves you. Our current understanding of the mechanisms underlying sound localisation suggests that we use different techniques for locating sources in the horizontal plane and vertical plane. 11.4 Signal duration Since hearing is largely a matter of stimulus reception over time, we would expect time to influence the perception of sound. It has been known for many years that both absolute thresholds and the loudness of sounds depend upon signal duration. The studies of absolute threshold described earlier were all carried out with tone bursts of relatively long duration. For durations exceeding 500 ms, the sound intensity at threshold is roughly independent of duration. However for durations of less th 11.3 Frequency selectivity In preceding sections we examined two ways in which the auditory system may code frequency information: the place theory and phase locking. In this section we will look at the psychophysical evidence for place coding on the basilar membrane by examining the ability of the auditory system to resolve the components of sinusoidal waves in a complex sound – a phenomenon known as frequency selectivity. The perception of a sound depends not only on its own frequency and intensity but also o 3.7.1 Summary of Sections 3.4 to 3.7 Hair cells are found in the organ of Corti and run the length of the basilar membrane. They transform mechanical energy into neural signals. When the basilar membrane vibrates in response to sound, hair cells located at the site of maximal vibration on the basilar membrane are stimulated. This means that the mechanical properties of the membrane allow the auditory system to distinguish one frequency from another by the location on the membrane that is maximally excited by a particular f Summary The ear is made up of the outer, middle and inner ears. The outer ear consists of the pinna, the external auditory canal and the tympanic membrane. The middle ear is air-filled and contains the middle ear ossicles. The inner ear is fluid-filled and contains the cochlea, the semicircular canals and the vestibule. Sound in the external environment is channelled into the auditory meatus by the pinna and impinges on the tympanic membrane causing it to vibrate. These vibrations are transmitt
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