Radiation, even in small doses, can cause cancer in humans and other living things
Alpha radiation is responsible for most of the damage of DNA in living cells
Although a reasonable and simple question, this query is difficult to answer because elements are dangerous for different reasons. Following are only some ways in which elements can be dangerous..ToxicityTechnically, anything is toxic (even water) if consumed in large enough quantities. Following is an incomplete list of known toxic elements. (Source: http://chemistry.about.com/od/toxicchemicals/a/toxicelements.htm). Elements marked with an asterisk (*) are both toxic and radioactive. AluminumAmericium *AntimonyArsenicBariumBerylliumCadmiumHexavalent Chromium Cr6+LeadMercuryOsmiumPolonium *Radium *ThalliumThorium *VanadiumUranium *.RadioactivityThere are also many radioactive elements, which may also be harmful, even if they are not toxic. The danger due to radioactivity depends upon both the half life of the element, as well as the decay mode. According to Rankopedia, the most dangerous radioactive elements are, in order: PlutoniumUraniumPoloniumFancieRadonNeptuniumTechnetiumAstatineCaliforniumEinsteiniumRadiumBerkeliumBismuthAmericiumThoriumMendeleviumDubniumCuriumRoentgeniumUnunquadiumActiniumUnunoctiumSeaborigiumProtactinium.ReactivityElements that are highly reactive are more dangerous because the interact, sometimes violently, with many common substances, including water. The resulting chemical reactions can be harmful or fatal, depending upon the circumstances. Reactivity is always between two or more elements, so there is not necessarily one single most reactive element, however the more reactive elements include: FluorineCesiumFranciumBrominePotassium
you can't
Basically two ways: either by listing all the elements, or by specifying some rule for elements to be included. Listing all the elements only makes sense for finite sets.
Element 115, also known as moscovium, is a synthetic element that is highly unstable and rapidly decays into other elements. It is not naturally occurring in nature and its short half-life makes it unlikely to pose a significant danger. However, as with any radioactive material, proper handling and containment are necessary to prevent potential risks.
Because the elements can combine in many ways to form compounds, and compounds can be mixed in many differed ways. Moreover, some elements occur in different forms. The elements carbon and hydrogen alone combine for form thousands of compounds.
Their properties are used to classify elements. There are many ways to classify them. The simplest is to divide them into metals and non-metals. You can organise them according to reactivity. I suspect you may be thinking of the periodic table, though I tend to think of that as a way to organise our knowledge rather than a system of classification.
How are elements classified
every animal is dangerous in their own special ways
Bacteria can be dangerous in many ways. Some bacteria carry diseases that can cause severe illness or even death. Some bacteria causes food to spoil and can make drinking water unsafe to consume.
Walking
Some elements of business communication include a sender, receive and the message. Senders have different ways of reaching their audience to ensure their message is understood.
In some ways yes and others no. Dry ice can cause some serious burns to the skin while fire burns everything. So, basically fire is the more dangerous.