WHAT WE ARE MADE UP OF?
Atoms In reality
Never trust an atom because they make up everything
Nothing is isolated in the world. The previous blogs were an attempt to give an idea about an atom in line with the scientific way of approaching a concept. There is no need to read them to understand this but imagination is very important. This will explain how to identify different atoms and their identities which gives us the real picture of the atom.
ATOMIC IDENTITIES
Everything around us is made of atoms of ninety and other chemical elements. All the atoms of a particular element have the same number of protons in the nucleus (and that same number of electrons surrounding the nucleus). In other words, the proton number determines an atom’s identity. The chemical properties of each element how it interacts with other elements are determined by the arrangement of the outermost electrons in their orbitals.
There is a great deal of variety in the properties of pure elements. For example, at room temperature, some are invisible gases, while others are shiny, metallic solids or brightly colored liquids. Some elements are highly reactive, others inert; some have extremely high boiling points, others extremely low ones. The exact combination of physical and chemical properties is a result of the configuration of electrons around the nucleus, and the number of protons and neutrons in the nucleus can identify a pure element.
Most elements are rarely found pure. Instead, they exist in compounds, in which their atoms are bound tightly to atoms of other elements. Of the thirty or so elements that do sometimes exist naturally in their pure state, gold, copper, carbon, sulfur, and silver are relatively easy to identify by sight. To identify the majority of elements, which only exist in nature combined with other elements, you must first separate them into their pure state. Most metals, for example, exist as ores, their atoms typically bound to oxygen atoms.
ORIGIN OF ATOMS
All the matter around us is made of atomic nuclei plus electrons, often bound together as atoms (or ions or molecules). The number of protons in a nucleus determines the element to which its atom belongs. Some of the nuclei and therefore some of the elements date back to the first seconds and minutes after the beginning of time. Others were formed inside stars and yet others in extremely energetic supernovas. The rest are the result of radioactive decay.
ATOMS IN REALITY - STUFF AND SUBSTANCE
The reality of atoms is that they engage in a physical and chemical changes. This is very evident in the physical properties that we observe in solids, liquids, and gases.
SPACING OF ATOMS - DENSITY
Density is the number of atoms per unit volume. Density combines the idea of weight and size. I.e. when you say a kilogram of popcorn and dumbell is of the same weight but unexpectedly we can see that the dumbell is smaller in size for the same weight so the dumbell takes a much smaller volume. As all atoms have a certain weight, as density is related to both volume and weight then it must depend on how closely the atoms are spaced.
From the scientific examination, we can see that if the spacing is doubled between atoms then the density decreases by a factor of 8. This means that Aluminium is about a thousand times denser than air and has about the same atomic weight so the atoms of aluminum must be 10 times closer together than the molecules in the air.
Another main reason for this atomic size is the attraction of the nucleus. A million atoms together will form an object that is visible to us so when the atoms combine together the nuclear attractive pull should overlap with the outermost electrons to get the desired structure. Even a small change in the spacing will cause a great difference.
HOW CAN WE DEFINE SOLID, LIQUID AND GAS USING THE SPACING OF ATOMS?
It is obvious from the above discussion. When you can squeeze something? or is a sponge easy to squeeze or a steel bar? It is the sponge because the sponge has gaps in between them so technically you are squeezing the air out of the gaps and ultimately you can't squeeze it more because there is no more gap. So in air, the atoms are very far apart leaving lots of space between them, in a solid, the atoms are so close together that there is no room left for gaps. Then in liquid, the atoms are at an intermediate distance that they can be squeezed but it breaks down and join again.
ATOMIC MOTION AND TEMPERATURE
Atoms are particles so it is nature that atoms can move. They can move fast and slow and it all depends on the collision and pressure provided to the atoms. As we can't compress a solid anymore in our imagination let us take gas. At normal conditions, 50% of the nitrogen atoms have a speed greater than 450 meters per second. As we are dealing with a very large number of atoms we need to conceder the average value so we use statistics to calculate the speed, a number of particles, and so on. To say a single atom will never have the same speed because there are lots of atoms moving randomly thus they will collide with each other so while colliding there will be a drastic change in the speed. All this formulation of concepts rose from the kinetic theory which we introduced to see the world in a new way.
Now, what are temperature and pressure? while you hug someone your body feels a little warmer it is because you apply pressure. Now, Why do we feel warm when pressure is applied? It is because when we apply pressure the atoms will have less space to move so it will produce lots of collisions so from the conservation law the extra energy produce dut the pressure or the restriction provided in the spacing will cause the energy to release. So heat is generated. So from this, we can have a general statement, when there is an increase in pressure the atoms move fast so heat energy is liberated thus the temperature is increased and vice versa. The average speed also depends on the molecular weight of the atom. I.e lighter atoms will have more speed.
ATOMS IN REALITY - CHEMICAL IDENTITIES
ATOMIC SPECTRA - SPECTROSCOPY
To identify a particular element, scientists normally study the colored light in a spectroscope, which separates out the individual frequencies present (each one corresponding to a particular pair of energy levels). The same characteristic frequencies are behind many everyday phenomena, including the colors of fireworks and the orange color of sodium lamps used for some types of streetlights. Many of the elements discovered since the 1860s have been identified as new elements or have had their status as “newly-discovered” verified by variations of this technique, which is known as spectroscopy. the spectra are nothing but the distinct pattern of wavelength called a spectrum.
VALANCE
From the roots of Latin, literature valance means to be strong or to be well. But is science we cant take it literally. So in science valance means "the capacity of atoms to combine with other atoms to form molecules" Due to this valance we are ab;e to find out the chemical behavior of atoms. In other words, it is the number of hooks an atom has available. The concept of valance is very useful because the valance of an element tends to be the same in a wide variety of chemical compounds.
Valance is a number that ranges from 1 to 7. The valance of the oxygen atom is 2 and the valance of the carbon atom is 4 so we expect one atom of carbon to combine with two atoms of oxygen thus forming CO2. In general, valance is the number of atoms in the outermost shell ( a shell can only have 8 electrons at the most). The elements which have valance 0 or 8 are called noble gas they hardly react with the elements.
STRUCTURE OF THE ATOM IN A NUTSHELL
An atom consists of a tiny dense core called the nucleus surrounded by electrons. The number of electrons in a normal atom is equal to the atomic number of the element. The electrons are bound to the nucleus by electric forces. The electrons are arranged in groupings called shells, The shells have reasonably well-defined radii. There is a limit to the number of electrons that can be grouped into a given shell. The innermost shell K can contain only two electrons at most. The next shell L can hold no more than eight electrons and so on. The electrons in a given atom tend to be arranged with the shells of the smallest radii filled to capacity. The chemical properties of an atom largely depend on the outermost electrons.
