Like the two proverbial scorpions locked in a bottle, American and Soviet arms negotiators have concluded their first week of meetings here, managing to start feeling each other out on reducing atomic weapons in Europe without delivering a fatal sting to talks that will be both tough and politically crucial for both sides.

After a private meeting of the two chief negotiators Monday and full delegation sessions Tuesday and today, the mood is described as serious, business-like and favorable, at least from the standpoint of the talks being under way. It is also described as all-consuming in terms of the work required to bridge huge differences of view between the superpowers on almost every aspect of a difficult and technical subject.

From what little can be gathered, this first week of secret meetings had its ups and downs.

It was understood that U.S. chief negotiator Paul H. Nitze was quite pleased with his initial private meeting with his Soviet counterpart, Yuli A. Kvitsinsky, and a Soviet spokesman last Monday suggested the feeling was mutual.

Since then, nothing has been said publicly but it is understood that in the first full delegation session last Tuesday when both sides began laying out their generally well-known views, there were no suprises for either side but very little real dialogue.

It was more like people talking past each other and it is believed to have left the American team somewhat disappointed. Today's two hour and twenty-five minute session was understood to be somewhat of an improvement but there is a great sensitivity here to boosting expectations without sufficient grounds and the feeling is that it will take a number of additional meetings before the delegates begin revealing whether there is a willingness to bargain.

At stake in these negotiations is whether the United States and Soviet Union can get a grip on the atomic arms race in central Europe and reduce the risk that a nuclear war could get started there.

For the West, what is also at stake is the political cohesion and future of the 32-year-old North Atlantic Treaty Organization (NATO).

The Western alliance plans to install 572 new U.S. intermediate-range missiles in Western Europe beginning in 1983 unless these arms talks produce an agreement with the Soviets. Those missiles are meant as a counter to some 600 missiles the Russians already have deployed and trained on West European targets.

But the Western missile deployment plan is controversial among some of the populace in Western Europe and the Soviets have played on these fears in an effort to split the alliance and perhaps have public opinion force NATO from carrying out the plan.

Thus far, however, those Western governments that have agreed to base the U.S. missiles on their soil if the arms talks fail -- West Germany, Britain and Italy -- are holding to their pledge. It is also clear from a recently published official Soviet book called "The Threat to Europe" that Moscow is indeed worried about the new U.S. weapons because they can strike deep into the Soviet homeland quickly and accurately from those European bases.

It is these factors that have produced at least the sense here that there is more than just public opinion to be dealt with; rather, that there are real issues that both superpowers must take into their calculations about the balance of power in Europe.

The talks here are being carried out behind closed doors and after the first private meeting between Nitze and Kvitsinsky, Nitze took the unusual step of announcing publicly that there would be a complete news blackout on the talks, at least here.

It is normal for the details of arms negotiations to be carried out secretly. Though there ultimately were many leaks of information, the SALT talks on the big intercontinental-range strategic missiles and bombers that went on for years here and in Vienna also were carried on behind closed-doors.

But what is different now is the contrast between the official silence here and the extraordinary degree of public interest, especially in Western Europe, about what is really going on here and what the results, good or bad, will mean for the continent. The interest seems much more intense and personal than that which accompanied the SALT talks, which dealt with what seemed a less realistic possibility that Washington and Moscow might someday lob nuclear missiles at each other across the poles of the earth.

Nevertheless, the throng of reporters and television cameras that were here to record the official opening of these negotiations is now all but gone.

Each Tuesday, the limousines of the Soviet delegation pull up in front of a nondescript office building here occupied in part by the U.S. Arms Control and Disarmament Agency. The two sides meet around a long wooden conference table in an eighth floor conference room with sports prints of ice hockey, American football and tennis on the wall. They look out on an extraordinary picture-window view of sparkling Lake Geneva with the snow-laden French Alps in the background. It is an unusual view for people meeting to talk about atomic bombs.

Each Friday, the American limousines pull up to Villa Rosa, the Soviet compound about a half-mile away, for the next meeting. It is a much more elegant building, but without the view.

The Soviets, perhaps anxious to say something publicly, today issued a statement thanking all those who sent letters and telegrams expressing wishes for success of the negotiations. "As far as the Soviet side is concerned," the statement said, "it will do everything . . . to achieve positive results" at the negotiations.

The twice a week sessions, at least tentatively, are expected to continue until a Christmas break that may last until after U.S. Secretary of State Alexander M. Haig Jr. and Soviet Foreign Minister Andrei Gromyko meet here Jan. 26-27.

Since those Haig-Gromyko talks will deal with the broader questions of U.S.-Soviet relations and the possible resumption of the strategic arms talks, they could also have a bearing on the course of the missile talks here. Some sources, however, doubt that these European-based talks will be quickly merged into the broader SALT discussions.