| A | B |
|---|
| substance that cannot be chemically broken down into simpler substances | element |
| How many elements are there? | 114, the first 92 are found in nature and the rest are made by scientists |
| Most elements are ______ at room temperature | solids |
| Which elements are liquid at room temperature? | mercury and bromine |
| Which elements are gases at room temperature? | oxygen, hydrogen, helium and neon |
| What is all matter made of? | elements |
| What are some substances that are made up of more than one element? | water, salt, sugar |
| atom | smallest part of an element that can be identified as that element |
| Who was the first person to suggest the idea of atoms? | Democritus |
| What does the word atom mean? | "cannot be divided" |
| What was Dalton's theory called? | Atomic theory of matter |
| What is the atomic theory of matter? | All elements are composed of atoms that cannot be divided or destroyed, Atoms of the same elements are exactly alike, atoms of different elements are different from each other, The atoms of 2 or more elements can join together to form type so matter called compounds |
| What special tool is used to take images of atoms? | STM, scanning tunneling microscope |
| Particle Accelerator | a device used to increase the energy of electrically charged particles |
| nucleus | center or core of an atom |
| proton | particle that has a postive charge |
| nuetron | particle that has no charge |
| electron | particle that has a negative charge |
| What is the structure of an atom? | An atom has a nucleus, protons, nuetrons, and electrons surrounding it. |
| Thomson's Model | the first scientist to suggest that an atom contains smaller particles , J.J. Thomson thought that an atom is made up of a positively charged material with negatively charged particles scattered evenly throughout |
| Rutherford's Model | An atom is mostly empty space where the positively charged particles are contained in a small central core -nucleus, the negatively charged particles were attracted to the poitively charged particles found in the nucleus. this attraction holds the negatively charge particles in the atom |
| Bohr's Model | The electrons are found in different energy levels. Electrons move around the nucleus in dfferent orbits |
| Modern Atomic Model | The location of the electrons cannot be known , energy levels are used to predict the palce where an electorn is most likely to be found outside of the nucleus -this is called an electron cloud The nucleus contains protons and nuetrons |
| subatomic particles | quarks and leptons , quarks make up protons and nuetron, leptons make up electrons |
| atomic number | number of protons in the nuclues of the atom |
| Why is the atomic number of an element important? | It identifies that element, no two elements have the same atomic number |
| Why is an atom nuetral( has no charge)? | An atom is nuetral because the number of protons and electrons in an atom are the same and cancel is each other out |
| If we know the number of protons in an atom we also know the number of ? | electrons |
| atomic mass | total number of the protons and neutrons in an atom measured in atomic mass units ( amu) |
| Atomic mass units | amu, unit used to measure the total mass of protons and nuetrons in an atom |
| 1 amu = | mass of 1 proton or 1 neutron |
| the mass of 1 electron = | 1/1,836 amu |
| How do you find the mass number? | rounding the average atomic mass to the nearest whole number |
| How do find the number of neutrons in an atom? | mass number - atomic number = number of nuetrons |
| Dmitri Mendeleev | known for developing the first table of elements organized according to properties |
| energy level | place in an electron cloud where an electron is most likely to be found |
| electron cloud | area in an atom where electrons are likely to be found |
| Each energy level is a different ____ | distance from the nucleus |
| Where is the lowest or first energy level located? | closest to the nucleus |
| Where are electron with more energy found? | In energy levels farther away from the nucleus |
| How do the electrons fill up the energy levels? | in order beginning with the lowest |
| How many electrons can each energy level hold? | only a certain number, the first holds only two electrons, the second holds up to 8 electrons, the third holds upto 18 electrons, the fourth olds up to 32 electrons. |
| What happens when energy is added or removed from an atom? | this can cause the electrons in the atom to move from one energy level to another , an electron gains energy is jumps to a higher level, it loses energy it drops back to a lower energy level |
| chemical symbols | shortened way of writing the nae of an element |
| periodic | repeating pattern |
| group | vertical column of elemets in the periodic table |
| period | horizontal row of elements in the periodic table |
| How is a chemical symbol usually written? | From the name of each element, The first letter is capitalized and the second letter is written in lower case |
| How are the elements arranged in the periodic table of elements | in order of increasing atomic masses |
| Modern periodic table of elemets | the elements are arranged in order of increasing atomic number |
| How many columns are in the periodic table? | 18 columns |
| What are the columns in the periodic table called ? | groups or families |
| How are elements in the same group similiar? | they are similar physical and chemical properties and they have the smae number of electrons in their outermost energy levels |
| How many rows does the periodic table have ? | 7 rows |
| What is each row called? | a period |
| What is the pattern of th elements in a period? | Each period starts with an element that is a solid and ends with an element that is a gas and they also have the same number of energy levels |
| metal | element that has the property of shiny luster, ductility, and malleability |
| luster | the way a material reflects light |
| malleable | able to be hammered inot different shapes |
| ductile | able to be drawn into thin wires |
| nonmetal | element that lacks most of the properties of a metal |
| On the periodic table what does the zigzag line separate from Group 13-Group 16? | metals and nonmetals |
| Properties of nonmetals? | dull, brittle, cannot be made into different shapes or wires, poor conductors of electricity and heat and may exists at romm temperature as solids, liquids, or gases |
| halogens | elements that make up Group 17 in the periodic table, . they can vary their physical state from solid to gas at room temperature, change color when they change state, |
| noble gases | gases in Group 18 that have similar properties and atomic structure, |
| What is neon used for? | used in lights because it gives off a bright red glow |
| What is helium used for? | to fill balloons |
