Just create an account and sign in. Enrol and complete the course for a free statement of participation or digital badge if available. All atoms of the same element have identical atomic numbers, and are chemically similar, but they may not be identical in other ways. Figure 2f shows copper. All copper atoms have atomic number all their nuclei contain 29 protons. But they also contain uncharged particles called neutrons.
In natural copper, the atoms are of two kinds. One has 29 protons and 34 neutrons in the nucleus; the other has 29 protons and 36 neutrons Figure 4. The two different kinds of atom are called isotopes of copper.
The neutron has a mass very similar to that of the proton, so the two isotopes differ in mass. The sum of the numbers of neutrons and protons for a particular isotope is called the mass number. The two isotopes are written, and where the mass number and atomic number precede the chemical symbol as a superscript and subscript, respectively Figure 5.
The mass number of any isotope is equal to the relative atomic mass of its atom, rounded to the nearest whole number. Thus, the relative atomic mass of natural copper But although copper contains two different isotopes, each isotope has the same atomic number, and therefore a virtually identical chemistry.
As you work through this course you will need various resources to help you complete some of the activities. Making the decision to study can be a big step, which is why you'll want a trusted University. Take a look at all Open University courses. If you are new to University-level study, we offer two introductory routes to our qualifications. This means that transferring electrons from this level is very difficult. As a result, copper's metallic bonds only exist on this outer layer of free-moving electrons, a pretty weak bond as far as metals are concerned.
This is why copper is so soft and easy to bend and cut. This same free agent electron plays a role in oxidation , or rusting. When copper is exposed to water molecules two hydrogen, one oxygen , this free electron is transferred to a neighboring oxygen atom, bonding it into a molecule. If only one atom of copper bonds to an oxygen molecule, it is called cupric oxide. If two copper atoms bond to an oxygen atom, it is cuprous oxide. Cupric oxide is considered "fully oxidized," while cuprous oxide is still in an active state.
The key to cuprous oxide, the aspect that makes is extremely effective as a biocide, is that active state. It is still producing reactive oxygen species , highly reactive molecules. These are unstable molecules that cause damage to cell structures. When it comes to killing bacteria, you want highly reactive molecules.
They are very good at pulling away electrons, releasing free radicals, and generally smashing up their environment. In the case of a pathogen, they tear through membranes and destroy DNA-making machinery like a hot knife through butter. Copper needs to oxidize to reach the same level of toxicity, and while cupric oxide is oxidized, it's in a more stable oxidation state so it doesn't wreak the same havoc as his brother, cuprous oxide.
So why is cuprous oxide so toxic to bacteria and so safe for humans? Changing the number of neutrons determines the isotope. Ions are often formed in nature when static electricity draws electrons away from atoms. When you experience an electrical shock after touching a doorknob, you have released a stream of electrons, thus creating ions. In addition to being positively or negatively charged, ions can quickly bond with ions with the opposite charge. Some common compounds are made up almost entirely of chemically bonded ions.
For example, salt is made up of a repeating series of chloride anions and sodium cations. Other examples of important ions include electrolytes, such as chloride, potassium, magnesium, and calcium ions which are essential to health. Electrolytes in sports beverages help to hydrate the body.
Potassium ions help to regulate heart and muscle functions. Calcium is critical for bone growth and repair, and it also plays a role in supporting nerve impulses and blood clotting.
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