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Science term1

TermDefinition
What was the main weakness of the Rutherford model of the atom? That Rutherford’s model was incorrect when plied at the Electrons do not move around the nucleus in circular orbits.
Describe, with the aid of a labelled diagram, the modern view of the structure of the atom. Our modern view of the atom is that it consists of a positively charged nucleus surrounded by electrons. The nucleus contains two types of subatomic particles: protons, which are positively charged; and neutrons, which are not charged.
Name the three important particles that make up an atom. Protons, Neutrons and Electrons
Where is most of the atom’s mass located? nucleus
How are protons different from neutrons? How are they similar? The difference between protons and neutrons are that one has a positive charge and one has a neutral charge. The similarities between the two is that they both make up an atom.
Describe the differences between protons and electrons. The main difference. Protons are positively charged, and neutrons are neutral whereas electrons are negatively charged. Protons are found in the nucleus of the atom, and they reside together with neutrons. ... Protons are positively charged.
John Dalton model compared to the others John Dalton proposed that all matter is composed of very small things which he called atoms. This was not a completely new Greeks (notably Democritus) had proposed that all matter is composed of small, indivisible. thought he was crazy
How are isotopes of the same element different from each other? isotopes of an element have same atomic number(number of electrons/protons) but different atomic masses(number of electrons + neutrons). So, they are different from each other on the basis of number of neutrons.
In symbols, isotopes are represented as EZA, where: A = the mass number; the sum of the number of neutrons and number of protons in the nucleus Z = the atomic number; the number of protons in the nucleus E = the symbol of the element.
Why are the isotopes of some elements radioactive? These isotopes are called radioisotopes. Their nuclei are unstable, so they break down, or decay, and emit radiation. ... A: The nucleus may be unstable because it has too many protons or an unstable ratio of protons to neutrons.
A radioactive particle that has the same size and mass as an electron is called Beta particles
radioactive particle that is made up of two protons and two neutrons Alpha particles
The type of radiation that can penetrate the human body and can be stopped only by a thick shield of lead or concrete Gamma rays
A radioactive particle that can travel almost at the speed of light Neutrinos are subatomic particles that have almost no mass and can zip through entire planets as if they are not there. Being nearly massless, neutrinos should travel at nearly the speed of light,
The half-life of an isotope of tritium is 4500 days. How many days will it take an amount of tritium to fall to a quarter of its initial mass? 1 half-life is 4500 days, so it must take 2×4500=9000 days for the sample of tritium to decay to a quarter of its initial mass what is the half-life of this isotope? 4 How many radioactive particles would be left after five minutes?
Describe three uses of radioactive elements. to study living organisms, to diagnose and treat diseases, to sterilize medical instruments and food, to produce energy for heat and electric power.
How do radioisotopes used in food preservation stop food from spoiling? Food irradiation is the process of foodstuffs to gamma rays to kill bacteria that can cause food-borne disease, increase shelf-life same benefits as when food is heated,frozen, or treated with chemicals, but does not change the temperature
react in a reaction Reactants
are formed in a chemical reaction? Product
What happens to the atoms in substances that take part in chemical reactions? the atoms and molecules that interact with each other are called reactants. No new atoms are created or destroyed. Reactants contact each other, bonds between atoms in the reactants are broken, and atoms rearrange and form new bonds to make the products.
The law of Conversion of mass States that in a chemical reaction , the total mass of the reactant is the same as the total mass of product. e.g Can’t be destroyed or created
Law of constant proportions States that in a chemical compounds, the ratio of the element is always the same, no matter how it is formed e.g CO2 is always the same. On Carbon and two Oxygen
Would you expect the mass of the ashes to be the same as the mass of the paper The mass does not change, it’s just a reaction but no atoms were lost all created, in the laws of convention
The difference between endothermic and exothermic reactions lies in the words themselves. "Thermic" refers to heat, just as in the word "thermometer." "Exo" means "outside" and "endo" means "inside." Thus, an endothermic reaction pulls heat into an object or area, while an exothermic reaction expels heat.
What common property do some acids and bases have when they come into contact with solid substances? They both can be corrosive.
What is the difference between alkali and base? Alkalis can dissolve in water bases cant.
Ph acid or base less than 7 - acids more than 7- bases equal to 7?- neutrals
Explain why the chemical reaction between an acid and a base is called neutralisation. A neutral substance has a PH of 7 and if you react enough of an acid with a base you will get H20 which is neutral
What characteristics do all combustion reactions have in common? A combustion reaction is when a reacts with oxygen and releases a huge amount of energy in the form of light and heat. A combustion reaction always includes a hydrocarbon and oxygen as the reactants and always produces carbon dioxide and water as products
What are the products of all combustion reactions in which fossil fuels are burned Carbon, hydrogen, nitrogen, sulfur, and oxygen produce the following products during combustion
What is the fuel in the combustion reaction known as respiration? Respiration is the chemical reaction in which energy is released from a reaction between Oxygen (O2) and Glucose (C6H12O6) Respiration releases energy for cells from glucose.
Respiration is the chemical reaction that takes place in every cell of your body. State two reasons it is classified as a combustion reaction. Fart and breath
Created by: Leg111
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