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Chem/radioactivity
science quarter 1
Term | Definition |
---|---|
Define elements | The simplest form of matter, made up of only one kind of atom |
Define protons | Positively charged particles found in the nucleus |
Define neutron | Particle that is neutral and is found in the nucleus |
Define electron | Negatively charged particle found outside the nucleus |
What makes each element different? | The number of protons, neutrons, and electrons it has |
What are the 18 vertical columns on a periodic table called? | Groups |
Elements in the the same ____ have similar properties | Group |
What is group 1 called | Alkali metals |
What is group 2 called | Alkali earth metals |
what is group 17 called | halogens |
What is group 18 called | noble gases |
What are the horizontal rows on the periodic table called | Periods |
Elements in the same period have _____ properties | different |
How is the periodic table separated | it is separated(left to right) into metals, metalloids, non metals |
Metals are on the ___ side of the table | left |
Good conductors of heat and electricity | metals |
Properties of metals | Ductile, malleable, high density, shiny |
Elements on the right side of the table and Hydrogen | non metals |
Properties of non metals | poor conductors, brittle, low density |
Elements along the stair step line | Metalloids B,Si,Ge,As,Sb,Te,Po,At not Al |
can have properties of both metals and non metals | metalloids |
what is chemical activity? | how easily an element reacts to form other substances |
chemical activity depends on how easily it will gain, lose or share ___ with other elements | electrons |
what is the bottom left top right rule | The most active metals are at the bottom of a group, the most active non metals are at the top of a group. Noble gases do not follow the rule because they are all stable elements. |
How do you figure out which period an element is in | check which horizontal row it is in |
The P.T is arranged in order of increasing | atomic number |
An elements atomic number is the same as its number of____ | Protons and electrons |
an electron has a charge of | -1 and a smaller mass than a proton |
an atom is electrically neutral because the | number of protons equals the number of electrons |
how do you find the number of electrons in an element | look at the atomic number |
an element has 1 electron in the 4th energy level. this is its highest energy level. what period and group is this element found in | period 4 group 1 the number of electron shells equals the period the valance electrons equal the group |
what is the 2,8,18,32 rule | the first electron shell can only hold 2 electrons the second can hold up to 8 and so on |
which emission has the least penetrating power? | Alpha |
what particles are given off as radiation from the nucleus? | alpha particles, beta particles,or gamma rays |
Alpha particle | A positively charged particle, weakest of the 3, can be stopped by paper |
Beta particle | A negatively charged particle, faster and more powerful than alpha, can must stopped by aluminum |
Gamma ray | electromagnetic wave, most powerful, must be stopped by lead or concrete |
What is the modern model of the atom | A nucleus with proton and neurons, electrons on the outside |
a neutral atom contains 12 neutrons and 11 electrons. The nu,her of protons in the atom is | 11 protons |
Define radioactivity | spontaneous changes in the nucleus accompanied by the emission of particles as radiation |
Which elements are radioactive | elements 84-92(naturally occurring) and 93-118(synthetic). also all isotopes of synthetic elements are radioactive and some isotopes of other elements are radioactive (ex carbon 14) |
what is an isotope | Another from of an element with different numbers of neutrons The number of protons is the same, but the mass number is different (and nu,her of neutrons) that is why we refer to the atomic mass on the P.T as average atomic mass |
What is half life | The period of time when half of the nuclei of a radioactive substance would decay |
what would be the overall charge of an atom of an element with 9 proton 11 neutrons and 10 electrons | -1 |
lewis dot diagram | the symbol takes the spot of the nucleus and dots are used to represent the number of valence electrons |
how do you find the number of neutrons | subtract the atomic number from the mass |